The broadcaster and tastemaker, 57, has hosted the slot since 2005, and his final broadcast for the weekday show will fall on Friday 20 October.
Lamacq has taken the decision to step back to spend more time with his family – he is married to psychologist Dr Jen Wills; the couple share one daughter.
Instead of his daily show, Lamacq will return in January 2024 with a new programme, Steve Lamacq’s Teatime Session, which will air weekly on Mondays.
Lamacq said: “It’s been terrific doing six shows a week, but what with all the prep work for the programmes and the ever-increasing volume of new music to listen to, there’s not been nearly enough time left over for my family. And to be honest, after nearly 40 years at the coalface of new music, I think I need a bit of breather.
“Plus, there are other things I’m keen to do. Not least seeing if there’s a more practical role I can play in supporting the live music circuit and the venues across the country that I owe so much to.
“But of course, my heart still lives for discovering and nurturing new bands, so I’m really pleased that these changes mean I can stay at 6 Music, while allowing more time to go searching for emerging artists, who I’ll be channelling into the new Monday show. There’ll be live sessions, interviews, some amazing archive and fingers crossed, at some point, the future of rock and roll.”
BBC radio regular Huw Stephens, who is replacing Lamacq, called taking over from the presenter “an honour”, adding: “Steve has been a music mentor to all of us, his recommendations, thoughts and guidance in music is a huge part of who I am today and to call him a friend as well as a colleague means a great deal.
“I look forward to spending time with the 6 Music listeners every day, sharing new music and celebrating the music we love. So to everyone who’s asked me over the years, ‘When are you getting your own show on 6?’, the answer is, ‘Soon!’ See you on the airwaves!”
The BBC described Lamacq’s move as a “well-deserved” change.
Lamacq, who started out as a journalist at NME, has presented on Radio 1, Radio 2 and 6 Music. He has played an instrumental role in the careers of many artists over his career, including Blur, Pulp, PJ Harvey, Coldplay, Florence + the Machine and Fontaines DC.