Fleischman is perhaps best known as the short-lived lead singer for the rock group Journey in 1977 between the group's albums, Next and Infinity. He appeared in live concert performances with Journey and co-wrote and recorded numerous studio demo tracks during the band's early writing sessions for the upcoming album, Infinity. Three of those co-written tracks appear on the album: "Anytime", "Wheel in the Sky" (reaching #57 on the Billboard charts), and "Winds Of March".
The only officially released Journey song featuring Fleischman's vocals is "For You" which can be found on Journey's box-set release, Time3, as well as on Fleischman's 1979 solo album entitled Perfect Stranger. He may have also contributed to the track "Velvet Curtain" (also found on Time3) which was later re-written as "Feeling That Way" and credited to Aynsley Dunbar, Steve Perry, and Gregg Rolie.
While former Journey manager Herbie Herbert states that he was fired for personality differences, Fleischman maintains that he was already signed to another manager, Barry Fey, and left Journey over management complications but remained friends with the band.
In January 2005 when Journey received a star on the Hollywood Walk of Fame, Fleischman was one of Journey's especially invited guests at the Journey: Past And Present ceremony.
Fleischman was also associated with the English rock group, Asia, for a short time. Already known to bandmember Carl Palmer, John Kalodner of Geffen Records introduced him to Asia's John Wetton as the possible new lead singer for the group. After working on new material together, it became apparent to Fleischman that Wetton's voice was actually best suited for the material; after discussing this with the band, he amicably left the project and returned to America to pursue other possibilities.
He has also been part of the band Channel, along with guitarist Tony Berg, bassist Trey Thompson, and originally with drummer Art Wood (not to be confused with the singer Art Wood) . This line-up of the band wrote the song "The Way I Feel". By the time Channel's self-titled album was recorded in 1984 however, Thompson's former Black Rose band-mate Gary Ferguson had joined as drummer, and would later appear on Robert's solo album Dreaming in Tongues (2004). (In 2009, after many years out of print, Channel's self-titled debut album was reissued on compact disc in the UK by Rock Candy Records.)
In 1986, Fleischman appeared with the Vinnie Vincent Invasion, featuring the ex-KISS guitarist Vinnie Vincent, on their self-titled album and later on the unreleased album Guitars From Hell (1991). In 1996, Vincent released a compact disc called The EP, which featured Robert on vocals. The EP was also released under the name Euphoria. Although out of print on compact disc, Vincent has since made the Euphoria EP available as a download.
In 2004, Fleischman recorded an AOR version of the "Lord's Prayer" for Liberty N' Justice for their album Welcome To The Revolution. He also released this track under his own banner in both vocal and instrumental versions.
Fleischman is also known for scoring soundtracks for TV and film, notably That '70s Show and the pilot episode of SpongeBob SquarePants. Many of his ambient scores can be found on the solo albums Kinetic Phenomena and Electric Raindrops, (both 2004).
In early 2009, Fleischman announced the formation of a new band,