Gelb, a Temple University grad, first entered broadcasting with the campus radio station WHIP-AM as a sportscaster and later was named their sports director. He had an internship with WIP-FM in Philadelphia. Gelb was the afternoon host on WNJE-AM in Trenton from June 2016 to March 2018. He added duties as a host of a postgame show following Philadelphia Eagles games on WPEN-FM in Philadelphia.
He went to the national airwaves on CBS Sports Radio Network as a weekend overnight host. Gelb was promoted to evening host and later elevated to afternoon host. He added the role as a Sunday afternoon host during NFL season for several years.
Gelb found additional work at SiriusXM Radio. He was a host on NFL Radio channel and hosted a program on Mad Dog Radio. CBS Sports Radio Network rebranded itself in April 2024 and Gelb remained there as their afternoon host until December 2015.
He continues as an NFL studio host and men's college basketball studio host at Compass Media Networks. Gelb began as a Saturday mid-afternoon podcast host earlier in 2026 with 365 Sports and Rogue Media Network. He also has been a fill-in host on WEEI-FM in Boston since May.