His broadcasting career began at the age of 15, when he did on-air work for his high school radio station in Coventry, Rhode Island.

He then was hired by Charlie Roberts, founder of MotorNet in New Jersey, to be the radio network's Director of Affiliates and Associate Producer.

When NBC acquired rights to the second half of the NASCAR season, Bestwick was joined by Benny Parsons and Wally Dallenbach Jr. as the network's full-time broadcast team.

Bestwick also continued to work for Turner Sports, as TNT served as NBC's broadcast partner on cable.

On July 20, 2011, it was announced that Bestwick would replace Marty Reid for the 17 Sprint Cup races hosted by ESPN alongside Dale Jarrett and Andy Petree.

[3] Bestwick replaced Marty Reid as play-by-play announcer for the Sprint Cup Series races starting at the Brickyard 400, returning him to the position for the first time since 2004.

!On April 28, 2017, Bestwick confirmed that he was being released by ESPN after the 2017 IndyCar double-header Detroit Grand Prix and would call his last Indy 500.

[11] Bestwick also did PA work for IMS during the Month of May the same year in addition to the NASCAR-IndyCar doubleheader weekend in August.

[12] In the summer and autumn of 2022, Bestwick was a sideline reporter during the inaugural season of the Professional Bull Riders (PBR) Team Series.