Hip-hop DJ Westwood claimed that he has been "sacked" from the weekday 4pm-7pm slot, which he has held since September 2009.
Westwood wrote on Twitter: "It's official I've lost my afternoon voice due to schedule changes I will not be presentin 1Xtra Mon-Fri 4-7pm from Sept."
The veteran star then elaborated: "I've been sacked from 1Xtra Mon-Fri 4-7pm from sept #Westwoodyourfired. I don't like gettin fired #Westwoodyourefired - 1Xtra."
In an official statement, Westwood simply said: "It's been a lot of fun and a great experience."
The 54-year-old will not be leaving Radio 1 Xtra completely, however. Westwood will continue to present his Saturday night show simulcast on Radio 1 and Radio 1Xtra.
The BBC has also announced that Westwood will front a new Sunday evening programme between 7pm and 9pm.
Radio 1Xtra Controller Ben Cooper said: "Tim has proved to be one of the most influential figures in UK hip-hop and I'm delighted that he will continue to bring his wealth of knowledge and unique style to Radio 1 and 1Xtra across the weekends."
DJ Charlie Sloth will replace Westwood on Drivetime from September.
Watch a clip from Tim Westwood's famous freestyle sessions below: