Ullman was born in Eilat, Israel, to American parents Laura (née Ehrenkranz), a teacher, and Brian Ullman, a printer. He has a younger sister and younger brother named Tali and Nadav, respectively. After his first birthday, his family left their kibbutz in Israel for Norwalk, Connecticut, USA, and then to Fairfield, Connecticut the following year. When Ullman was younger, his father worked as a clown. While attending summer camp, he played Peter Pan, which helped him discover his talents in acting, singing, dancing, and reading drama novels.
Ullman was raised in the Conservative and Orthodox denominations of Judaism. His maternal grandfather, Joseph Ehrenkranz, is an Orthodox rabbi in Stamford, Connecticut. Ullman is a first cousin, twice removed, of Connecticut Senator Joe Lieberman. Lieberman's mother and Ullman's matrilineal great-grandmother were sisters.
Ullman taught himself how to play the trombone. Ullman was selected to attend the Hugh O'Brian Youth Leadership Foundation (HOBY) youth leadership program of Connecticut in March 2002 where he was selected as the "outstanding ambassador" enabling him to attend the HOBY World Leadership Congress in the summer of 2002. He went to Hillel Academy and is a graduate of Fairfield Warde High School. He was active in National Conference of Synagogue Youth.
Ullman's first professional role was as Louis in the national touring company of The King and I along with Jesse McCartney. Other productions he worked on include Peter Pan at the Polka Dot Playhouse, The Music Man with the New England Repertory Company, and Just People at the Long Wharf Theatre. He received a 1998–1999 Best Actor nomination from the Connecticut Critics' Awards for his character Stanley in Stamford Theater Work's A Rosen by Any Other Name.
Ullman is best known for his starring role as Phil Diffy, a teen from the year 2121 on Disney Channel's Phil of the Future, a series that debuted June 2004. He also starred as Roscoe in Disney's made-for-television film Pixel Perfect and as Sam in ABC Family's television film Searching for David's Heart (2005). Ullman was an identified member of the Disney Channel Circle of Stars, and appeared with other members of the Circle in the music video for "A Dream is a Wish Your Heart Makes," where he sang as well as played the drums. Ullman also appeared in the Law & Order: SVU episode "Obscene," in which his character rapes a teen star (Maggie Grace).
While Ullman previously went by the stage name Ricky, he started using his real name in 2006 when he guest-starred on an episode of House and continued to use Raviv on all projects since. In 2008, he appeared in an episode of the television series The Middleman.
He played the character Kip in the sitcom Rita Rocks on Lifetime. He is Rita's daughter's boyfriend and plays the drums in Rita's band. The show was canceled after two seasons. Ullman was later featured in a television commercial for State Farm Insurance alongside John C. McGinley and in a commercial for Cox Cable. From January 2012 to March 24, 2012, Ullman starred as the character Alex in the New Group's production of Russian Transport Off-Broadway in New York. On April 30, 2012, it was announced that Ullman joined the cast of Alena Smith's new Off-Broadway play The Bad Guys. It began performances on May 22 at the McGinn/Cazale Theater on the Upper West Side in New York City.
In June 2006, Ullman and a few of his friends created a parody hip-hop music video, "Pointy Hat (The Boat Song)," under the name the Webee Boys. The video was viewed over 300,000 times since it was posted to YouTube on June 26, 2006. Two other music videos were released, "Refrigerator (Gangsta' Way)" in August 2006, which was viewed over 100,000 times and "Bop It (Webee Anthem)" in March 2007. The Webee Boys have performed live exclusively at the Gig in Hollywood, California.
In December 2006, Ullman met actor Douglas Smith of Big Love fame and together they formed a band called Goodbye Ian. The group expanded to as many as seven people and later changed its name to His Orchestra. Ullman plays drums and glockenspiel in the band, which released its debut album, Field Guide to the Wilds, on February 24, 2009.
Both groups communicate online through the social networking Web sites MySpace and Twitter. Raviv is currently in the band Reputante on Julian Casablancas' Cult Records.
Ullman speaks fluent Hebrew and keeps a kosher kitchen.