Simba and Kion have a close and affectionate father-son relationship. Kion loves his father immensely and will do anything in his power to make his father happy. Simba also loves his son dearly. In The Lion Guard: Return of the Roar, Simba becomes annoyed with Kion when he and Bunga unintentionally disrupt his lecture with Kiara and ends up having to separate his two children when they argue.
When Rafiki declares that Kion is ready to lead the Lion Guard, Simba is at first worried about this, thinking that due to Kion being a cub, he is not ready to handle the responsibility. But changes his mind when Nala encourages him to listen to Rafiki. After seeing that Kion has chosen Bunga, Beshte, Fuli, and Ono to be part of The Lion Guard, Simba was not pleased. He tells his son that the Lion Guard has always been made up of lions and scolds Kion for treating his role of leader as a game and tells him to take his responsibilities seriously as Kiara does with hers. However, in truth, Kion did take his duties as the leader of the Lion Guard very seriously.
However, after Kion and the Lion Guard save Kiara from a gazelle stampede and chase away Janja and his clan. Simba realizes that Kion was wise enough to have chosen his friends to be in the Guard and expresses pride in his son and accepts the new Lion Guard. Ever since then, Simba has helped Kion defend the Pride Lands on a few occasions, as seen when he helped Kion defeat Reirei and her jackal family during the Kupatana celebration and, he even become a leader of the guard temporarily while Kion was away with Nala and Kiara on Udugu.
Simba shows great pride towards his son for his duty as leader of the Lion Guard and has great faith in them whenever their protecting the Pride Lands.
After Scar returns to the Outlands, Simba plans on helping his son and his Lion Guard, defeat his evil-uncle, which eventually comes to pass months later, but at the cost of Kion receiving the Mark of Evil during the battle, which prompts him to journey to the Tree of Life with Simba supporting this desicion, not wanting his only son to fall down the same dark, cruel and murderous path that his uncle did at Kion's age.
A few months later after Kion returns to the Pride Lands, he and Nala are happy to see their son again, and even more happy to see him marry Queen Rani and become King of the Tree of Life.
Kiara and her father Simba are shown to have a loving father-daughter relationship. Although she won't admit it, she loves being "Daddy's Little Girl," as Kovu once called her. Simba likewise, absolutely adores his little princess, albeit often to the point of being fiercely overprotective. Some point after that fateful day whereby she met Kovu, Kiara became more accepting of her destiny as the Pride Lands's future Monarch. Simba taught her the importance of family, unity, and destiny in their Father-Daughter duet song, "We are One." She now enjoys learning about the importance of ruling from him. She loves her father deeply and becomes worried when he is hurt as seen when she stays by his side the whole day when he is sick.
Simba later accepts Kiara's relationship with Kovu, the adoptive son of his evil-uncle Scar, and proclaims them his new successors to Pride Rock.
Simba often finds Bunga annoying at times due to his impulsive nature and his often disrespectful attitude. When the pair were trapped in Nandembo Caverns, the pair erupted into a fiery argument which made them split up. Here, Simba began to realize that the honey badger was not only still a citizen of the Pride Lands, but also his subject (not to mention his son's best friend), and thus it was his duty to find and protect him. After hearing him sing Hakuna Matata, he sang it with him, and the pair began to bond, having both been raised by Timon and Pumbaa. The pair even considers each other brothers, though this is not always brought up between them.
Although Simba still finds Bunga irritating from time to time, the pair has a much better understanding of one another than they did before the incident.
When Simba was a cub, he loved his uncle greatly, unaware of how much Scar hated and resented him for being next in line. Simba later ran away after his father was killed in a stampede, and Scar took over the Pride Lands. Some years later, when he had fully matured, Simba returned to Pride Rock only to discover the truth about Mufasa's death at the claws of Scar, and engaged in a ferocious battle to reclaim his throne. Simba won the fight, though he always remembered what his uncle had put him through, relieved that his son vowed to never become like his great-uncle. After being informed that he has returned, Simba is determined as his son to defeat him once and for all. Simba sees him again in The Fall Of Mizimu Grove, marking their first encounter with each other ever since their battle.
Months into the battle between the Pride Landers and the Outlanders, Simba becomes more determined to defeat Scar, and declares that they will go to war with Scar's army in the Outlands, which soon leads to the fall of Scar's spirit once and for all.
Simba had a strong bond with his father Mufasa when he was a cub and looked up to his father in every way. However, when Scar murdered Mufasa it broke his heart and soon ran away in fear, thinking that it was his fault.
When Simba was an adult, it was his father's spiritual guidance that eventually convinced Simba years later to reclaim the throne from Scar.
In The Wisdom of Kongwe, Simba and Kion consulted Mufasa after the revelation of Scar’s return, proving that he still has faith in his father's wisdom, and will call him when needed.
As an offspring of Zira's, Simba banished Vitani to the Outlands with her family.
Vitani was one of the first to agree with both Kiara and Kovu that the war needed to end between the prides, and Simba has since accepted her into his, forgiving her for any past misdeeds. Vitani soon became the leader of the Lion Guard in Kion's abscence, to which Simba came to peace with until Kion's return. He soon watched and Vitani became Kion's successor, whilst Kion himself left the Pride Lands to become King of the Night Pride.
As an offspring of Zira, as well as the adoptive son of Scar, Simba banished Kovu to the Outlands with the rest of his family.
After Kovu and Kiara were able to put a stop to the war, Simba has since taken to Kovu as his son-in-law, trusting him with his daughter and as his eventual successor as king of the Pride Lands to reign alongside Kiara, the future queen regnant.
When he was a cub, he did not care for the bird at all, but once he returned to the Pride Lands, he accepted him as a loyal friend to where he becomes concerned about him when he is not on time for the Morning Report.
Although at first Simba wasn't too keen on the idea of her being on Kion's Lion Guard, Fuli is shown to have a good relationship with Kion’s father, Simba. Simba trusts Fuli a lot, enough that he specifically asks her to bring his son home safely when they leave for the Tree of Life. In Battle for the Pride Lands Simba asks Fuli to bring Kion home safe.
Although at first Simba wasn't too keen on the idea of him being on Kion's Lion Guard, Beshte is shown to have a good relationship with Kion's father. As a member of the Lion Guard, Simba trusts Beshte's abilities.
Ono is a loyal friend to the king as seen when Ono spoiled Kiburi's plot to murder Simba and when he helped save him in The Scorpion's Sting because he and the Guard retrieved the ash to Pride Rock. When Simba also temporarily leads him, Beshte, Bunga, and Fuli in The Trail to Udugu while Kion, Kiara, and Nala were away for the Udugu event. The king occasionally compliments him on his keen sight.
Simba and Basi are allies since at The Kupatana Celebration he told Beshte his father's singing was sounding good.
Basi respects Simba, but isn't afraid to speak out when he feels that he has been wronged. An example would be in The Fall of Mizimu Grove, where Basi didn't like it when Simba or Kion didn't tell them that Scar was back.
When Kion introduced his parents to Ajabu, he explained that Ajabu had come to the Pride Lands as a visitor, but wished to stay with their blessing. Simba and Nala warmly agree, and are as such on good terms with the okapi.
Mbuni was shown bowing to Simba during Duties of the King, first showing her respect for her King. When a mudslide threatened her eggs, Simba leaped in with Beshte, Bunga, Fuli, and Ono to help save them. Mbuni was honored to have her eggs saved by the King, and once again bowed to him. She truly respects Simba.
Not only are the birds of the Pride Lands fans of Hadithi, but the king of the Pride Lands is a fan of Hadithi too as he believed him to be a hero when they first met and has, in fact, praised him twice in the episode,Ono's Idol. He later watches the eagle praise Ono for his true bravery in the Royal Mud Print Ceremony.
Simba at first distrusted Makuu, as he had, at one point, threatened his mate, Nala.
Simba was the first animal at the Savannah Summit to believe that Makuu had changed for the better when the crocodile actually reformed. When Kiburi lost the mashindano and attempted to kill Simba, Simba believed Makuu was innocent, showing his trust of the crocodile.
After Simba and his son talk to Mufasa, the former recall his knowledge of the wisest animal in all the Pride Lands, so he sends Fuli and Makini to bring Kongwe to Pride Rock. Later she has arrived just in time, he is confused about what it means.
Laini and Simba are on good terms since she and her galagos are Pride Landers. Laini's groups sing Good King Simba at the Kumbuka celebration. In the Fall of Mizimu Grove Laini didn't like it when Simba didn't tell the Pride Landers that Scar was back. Her group was thinking about leaving however they decided to stay.
Thurston and Simba are on good terms since he and his herd are Pride Landers. He attempted the Kumbuka celebration. He was scared that Scar was back and was mad that Simba didn't tell them. However, he and his herd stayed in the Pride Lands.
Janja hates Simba because he is king of the Pride Lands and forbids him and his clan from entering the Pride Lands. This could likely also stem from Janja being descended from Shenzi, Banzai, and Ed's clan, the same hyena clan who aided Scar in murdering Mufasa, exiling Simba, and ruling the Pride Lands before betraying and murdering his uncle himself.
Janja later aids the ghost of Scar in attempting to kill Simba and take control of the Pride Lands.
In Battle for the Pride Lands Simba listens to Janja when he says he knows how to defeat Scar. Although the information Janja gives them (Kion using the Roar to destroy Scar's ghost in the volcano) is a lie, fed to him by Scar, ultimately Scar is defeated and Janja officially gains Simba's trust.
Zira is of the firm belief that Scar should be ruling the Pride Lands. As such, after Simba took over, she attacked Simba, but the King overpowered her.
With Zira refusing to compromise, Simba had no choice but to banish her and her followers into the Outlands, where they were later exiled from later by Kion.
Years later, Zira sends Kovu, her youngest son who was previously adopted by Scar, to infiltrate the Pride Land in order to overthrow Simba, by gaining his and Kiara's trust. However, after Kovu falls in love with Kiara, and befriends Simba, a betrayed Zira attempts to frame Kovu in Simba's attempted murder, and later leads an assault on Simba's pride, but is stopped by Kovu and Kiara who convinces Simba to accept the Outsiders. Whilst Vitani accepts her new line, later becoming Simba's son's successor as leader of the Lion Guard, Zira refuses, making one last attempt on Simba's life, but is battled and defeated by Kiara, completing her journey in the Circle of Life.
As a follower of Zira's, Simba does not trust Lioness and banished her to the Outlands. However, after Kiara and Kovu stopped the fighting between the two prides, Simba came to see he was wrong to exile her and the other Outsiders and thus welcomed her and the others back into his kingdom. Lioness has since forgiven Simba for exiling her and her pride and now serves him faithfully.
As an offspring of Zira's, Simba banished Nuka to the Outlands with his family for siding with Scar. Years later when Nuka is a young adult, he leads an ambush against Simba after Kovu betrays them, resulting in Simba unintentionally killing Nuka.
After his son allowed Reirei's son into the Pride Lands, Reirei and her family proceeded to break Kion's trust in her and gatecrashed the Kupatana celebration. After they were contained, she was met with anger from Kion, who refused to listen to any more of her lies and demanded that she and her family return to the Outlands. As Reirei continued to try and manipulate his son, Simba came to back him and ordered the jackal family to leave the Pride Lands before scaring them off with a roar.
Simba originally suggested that his son save Dogo in the Outlands in the spirit of Kupatana, but he and his family later invaded the ceremony instead. Simba ordered that the jackals leave the Pride Lands, and never return.
Goigoi and his family almost destroyed Kupatana, having initially been allowed to stay in the Pride Lands. As a result, all potential trust Simba had in the jackals was lost, and he ordered them to leave the Pride Lands.
After being told by Ushari that if he harmed the king he could rule the Pride Lands, Kiburi planned for his three minions to kill him while he fought Makuu. After the Lion Guard spoiled his evil plot, Simba became enraged. Not long after the plan was foiled, Kiburi lost the Mashindano, and, with Makuu's permission, Simba banished Kiburi and his followers from the Pride Lands.
At Kiburi's orders, Tamka was tasked with taking down Simba during the Mashindano. The plan failed when the Lion Guard got involved, and Simba banished him to the Outlands, along with the other crocodiles that were involved in the scheme, no longer trusting them.
At Kiburi's orders, Nduli was tasked with taking down Simba during the Mashindano. The plan failed when the Lion Guard got involved, and Simba banished him to the Outlands, along with the other crocodiles that were involved in the scheme, no longer trusting them.
Sumu is the scorpion that was sent by his uncle to poison him. After being poisoned by him, the king becomes very weak until shortly after the Lion Guard and Makini return to Pride Rock with the Volcanic Ash.
Simba hates Ushari since he was working for Scar. In "The Scorpion's Sting Ushari and the rest of Scar's Army tries to make Simba ill and weak. In "Battle for the Pride Lands" Simba disliked Ushari more after he gave Kion his scar.