As a human, in the childhood, Leo was 5-year-old boy with bluish teal eyes and brown spiky hair. He wore a red shirt and blue pants. He lived in New York City.
As a turtle, Leo has blue eyes, and lime green color skin, with a short reptilian tail. His facial expressions, arms, and tail are also very similar to Shoutmon from Digimon Fusion. He wears a blue mask where the tails length range between Raph and Mikey. Like Raph, Leo doesn't have much changes to his physical appearance like all his previous incarnations. His height ranges between Raph and Donnie's. He is a little much taller than Donnie and Raph. He is lean, looks more mysterious, and is handsome.
Leo is the most serious and disciplined out of all the turtles and is of course their leader. He has a lot of responsibility on his hands, which can sometimes overwhelm him. He watches a T.V Show called "Cyberchase Monsters" and wants to be just like the captain he sees on T.V. Overall, Leo acts as a big brother to the turtles and as a most trusted son to Master Splinter. He was chosen to be the leader because of his willingness not by his skill. Leo also has a huge crush on April O'Neil that was love at first sight. Much like in 2003 series, he has a very close bond with Splinter, and has a strong sense of honor and ethics, along with being a dedicated follower of the Bushido code. Episodes that deal with the Shredder and honor usually also focus on Leonardo, and he is often the Turtle who "saves the day". Leonardo is a more sensitive, self-doubting character than in previous incarnations. Raphael often quarrels with him and resents his leadership, sarcastically calling Leonardo "Fearless Leader", although the two are shown to be very close at times. Leo is the most Mature out of all his brothers, aside from Donnie, always acting like a guide and sometimes even a parent to his brothers. He is very protective of his siblings and is willing to do anything for them. Unlike all his incarnations, Leo is somewhat a sci-phy geek, aside from Donnie...though he's more of a techy geek. Leo loves "Cyberchase Monsters" and tends to try to be like the hero on there, much to the annoyance of Raph. He also tries too hard to act like a hero and says cheesy lines, which annoy Raph. Despite this, his brothers view him as a pillar of strength and are at a loss when he is injured or absent. One of Leonardo's most prominent qualities is his determination to believe the best in people, even potential enemies (i.e., Karai, and Traximus). At times, Leonardo is shown to be very hard on himself, as he feels that a lot is expected of him. As in the Mirage comics, Leonardo is ambushed and seriously injured by the Foot Clan and he feels he let his family and himself down. He has the same feelings after the final battle with the Shredder-his anger and self-doubt was caused by Karai, whom he believed was an honorable ally, but she was unable to go against her master's orders, eventually causing her to stab Leonardo (unintentionally). Leonardo eventually joined the Utroms and became one of the guardians.
- Unlike his other incarnations, this version of Leonardo has a crush on April O'Neil.
- Leonardo has used Mikey's catchphrase once, Cowabunga.
- This version shows Leo's more teenage side because in previous incarnations in this franchise, Leo's personality was a more of a grown-up part.
- He can hold his breath underwater for about 15 minutes.
- His swordsmanship is unmatched.
- The blue in his bandana represents his main emotions: calmness and leadership.
- His main elements are water and ice.
- His main season is winter.
- He seems to have a relationship with Splinter, like Father, like Son.
- He seems to have a relationship with Mortu, like Uncle, Like Nephew.
- Leo's eye color goes from teal to blue.
- Leonardo is voiced by Benjamin Diskin.