Leguizamo was born in Bogotá, Colombia to Alberto and Luz Leguizamo. His paternal grandfather was of Italian and Puerto Rican descent; his maternal grandfather was Lebanese. Leguizamo's father was once an aspiring film director and studied at Cinecittà but eventually dropped out due to lack of finances. When Leguizamo was three years old, his family emigrated to the United States and lived in various neighborhoods of Queens in New York City. Leguizamo attended the Joseph Pulitzer Middle School (I.S.145) and later the Murry Bergtraum High School. As a student at Murry Bergtraum High School, Leguizamo wrote comedy material and tested it out on his classmates. He was voted "Most Talkative" by his fellow classmates. After graduating from high school, Leguizamo enrolled at New York University where he took theater classes.
Leguizamo started out as a stand-up comic doing the New York nightclub circuit. In 1984, he made his T.V. debut with a small part in Miami Vice. His other early roles include: an extra in Madonna's Borderline video (1984), as a friend of Madonna's boyfriend; Mixed Blood (1985); Casualties of War (1989); Hangin' with the Homeboys (1991); the robber in Regarding Henry (1991) and Night Owl (a.k.a. Nite Owl) (1993), which was filmed from 1991-1992. In 1991, he also wrote and took part in the Off-Broadway production Mambo Mouth, where he played seven different characters. Mambo Mouth won an Obie Award and an Outer Critics Award. He was listed as one of 12 "Promising New Actors of 1991" in "John Willis' Screen Worlds Vol. 43".
In 1993, Leguizamo wrote and participated in Spic-O-Rama, where he made fun of the stereotyping of Latinos in the U.S.. The production won a Drama Desk Award and four Cable ACE Awards. Leguizamo also played the role of Luigi Mario in the 1993 movie production Super Mario Brothers, starting his acting career in Hollywood. Leguizamo also created, executive produced, wrote for, and starred in the 1995 Latino-oriented variety show called "House of Buggin'". The show showcased Leguizamo's well-known ability to assume a wide variety of colorful, energetic characters. The show ran less than a year on Fox. Other movies included Carlito's Way (1993) as Benny Blanco alongside Al Pacino, To Wong Foo, Thanks for Everything, Julie Newmar (1995) as Chi Chi Rodriguez, Romeo + Juliet (1996) as Tybalt, Prince of Cats, The Fan (1996) as Manny, Executive Decision (1996) as Captain Rat, The Pest in 1997, as con man Pestario "Pest" Vargas, Doctor Dolittle (1998) as Rat #2, Summer of Sam (1999) as Vinny, and Moulin Rouge! (2001) as Toulouse Lautrec.
In 2000, Leguizamo played two genies in the Emmy Award winning miniseries Arabian Nights. Leguizamo has participated in over 53 films, including The Alibi, where he played the role of "Hannibal". In 1998, he debuted on Broadway in the production of Freak, which was also turned into an HBO film by director Spike Lee. Leguizamo has produced 10 films, including Piñero and made 13 TV guest appearances. In 2000, he wrote and participated in Freak, which was basically about his whole life experience with his family, how he had a troubled family, and a messed up life. He voiced Sid the sloth for 2002's Ice Age and has done so in both Ice Age 2: the meltdown and Ice Age: Dawn of the dinosaurs. In 2003, he wrote and participated in Sexaholix which basically explained his love life, and how he started a family. Later in 2003, he voice-acted Globox from Rayman 3. The game versions with his voice acting were PlayStation 2, GameCube, Xbox, PC, and Mac.
During the 2005-2006 television season, Leguizamo joined the cast of the show "ER", playing the emotionally disturbed Dr. Victor Clemente, a new attending who is keen on introducing the staff of County General to better ways of treating patients and cutting-edge technology. Clemente, however, was plagued with personal problems and was fired from the hospital near the end of the season. Dr. Clemente's departure from the show was a blessing for Leguizamo. He revealed to CraveOnline that he was not happy working on the television program. "I was depressed doing ER," he admitted, "I started gaining weight, I was eating donuts, I started smoking again. I’m eating McDonalds, things that I know when I’m depressed I do. I tried to kill myself internally."
In October 2006, Leguizamo's memoir, Pimps, Hos, Playa Hatas and All the Rest of My Hollywood Friends: My Life, was released. During an interview on Late Night with Conan O'Brien, Leguizamo stated that his memoir was very frank about odd experiences involving other celebrities and co-stars he had worked with. He claimed that working with Arnold Schwarzenegger was one of the most enjoyable experiences he had as an actor. He also said that Arnold's accent let him say things that others would think were sexist or homophobic if said by someone else, that Steven Seagal was an egotist with diva tendencies, and that Leonardo DiCaprio was a "patron of prostitutes".
In July 2007, Spike TV aired their dramatized series The Kill Point, starring Leguizamo, Donnie Wahlberg and Michael Hyatt. The show was an eight part series revolving around ex war veterans whose bank robbery went wrong, thus ending in a hostage situation. Despite high ratings, The Kill Point was not renewed for a second season. .