Born in Westchester, New York, Sabella graduated from Westlake High School in Thornwood, New York. Sabella then went on to graduate from the University of Miami, where he studied at the Department of Theatre Arts and performed at the university's highly-regarded Jerry Herman Ring Theatre.
His stage credits include The Robber Bridegroom (1978), Little Johnny Jones (1982), Guys and Dolls (1992), 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, Mousehunt and A Funny Thing Happened on the Way to the Forum. In the latter production, Sabella portrayed Marcus Lycus while Lane played Pseudolus.
On television, Sabella played store owner Donald Twinkacetti on Perfect Strangers (1986-1987). He also played Leo in the short-lived Nathan Lane situation comedy Encore! Encore! (1998-1999). Sabella also had a five-episode stint on Saved by the Bell as Leon Carosi, an uptight resort manager 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, 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 but memorable appearance as a naked man on a subway train in a 1992 episode of Seinfeld entitled, appropriately, "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).