Born in Westchester, New York, Sabella graduated from Westlake High School in Thornwood, New York and from the University of Miami, where he studied at the Department of Theatre Arts and performed at the university's Jerry Herman Ring Theatre.
His stage credits include The Robber Bridegroom (1978), Little Johnny Jones (1982), Guys and Dolls (1992) as Harry the Horse, A Funny Thing Happened on the Way to the Forum (1996), Chicago (1996), Man of La Mancha (2002, as Sancho Panza) and Sweet Charity (2005). Film credits include Quiz Show (1994) as the car salesman, In & Out (1997) as Aldo Hooper, Disney's The Lion King (1994) and multiple sequels and spin-offs as Pumbaa. He also has worked with Nathan Lane, who had voiced Timon, in Guys and Dolls, Mouse Hunt, The Producers (in a deleted scene) and A Funny Thing Happened on the Way to the Forum. In the latter production, Sabella portrayed Marcus Lycus while Lane played Pseudolus. Sabella also joined Lane for his Saturday Night Live monologue, where they sang "Hakuna Matata".
On television, Sabella portrayed apartment manager Lou Donatelli in the Jason Bateman comedy It's Your Move (1984–85). He also appeared in an episode of Cheers entitled "Love Thy Neighbor" (Season Four Episode Eight air date November 21, 1985) in which he played the role of a private investigator named Santo Carbone, who was Carla Tortelli's cousin. He played store owner and landlord Donald Twinkacetti on Perfect Strangers (1986–1987). He also played Leo in the short-lived situation comedy Encore! Encore! starring Nathan Lane (1998–1999). Sabella also had a five-episode stint on Saved by the Bell as Leon Carosi, an uptight resort manager and owner who employed the main cast's characters. Leah Remini was featured as his daughter. His other recurring roles include the lazy teacher Mr. Petrachelli on That's So Raven, the floundering attorney Harland Bassett on The Practice, and characters on Hill Street Blues and Newhart. In the Quantum Leap episode "Catch a Falling Star", he played the dual role of Manny, a stage actor, and Sancho Panza, Manny's character in a touring production of Man of La Mancha. Sabella had a brief appearance as a naked man on a subway train in a 1992 episode of Seinfeld titled "The Subway". He also starred in a series of television commercials for NyQuil cold medicine in 1994 and was recently seen in a MasterCard commercial (2007). He also did work as the guy from Lynx in 2003.
Sabella co-starred as Sidney Bernstein in the Broadway musical comedy Curtains, which opened officially on March 22, 2007 and ran until June 29, 2008.
Sabella voiced the character Siegecrafter Blackfuse in World of Warcraft: Mists of Pandaria.
He played the role of apartment building superintendent Leon in the 9th episode "Hold Outs" of the 6th season of the CBS police procedural drama Blue Bloods.
In 2015, Sabella reprised his voice role as Pumbaa in the TV pilot movie The Lion Guard: Return of the Roar.
In 2016, Sabella became a full-time cast member for the Disney Junior television series The Lion Guard.
Sebella met his wife Cheryl backstage during a broadway performance of A Funny Thing Happened on the Way to the Forum in 1996, they married in 1999. His wife also works as a computer programmer in their home town.1996 - Daytime Emmy Award - Outstanding Performer in an Animated Program - Nominated
2005 - DVDX Award for Best Animated Character Performance (Voice and Animation in a DVD Premiere Movie) - Nominated