According to the latest RAJAR data, the Absolute Radio digital spinoff topped 1m listeners to an average weekly reach of 1.02m, nearly double its audience of 564,000 in the same period last year.
The station has also now overtaken previous digital leader The Hits, along with popular digital station Planet Rock, which both suffered declines in their audiences.
Absolute Radio 90s had a weekly reach of 366,000 listeners, down 15% on the previous three months, while Absolute Radio 00s slumped to 120,000 from an audience of 200,000 in the second quarter.
The main Absolute Radio station on FM/AM saw its audience decline 3% year-on-year to an average weekly reach of 1.6m. Absolute intends to launch two stations dedicated to the 60s and 70s next month.
Buoyed by its exclusive Rugby World Cup rights, the UTV Media-owned TalkSport increased its weekly reach by 5.8% year-on-year to 3.13 million. This marked the station's highest-ever audience reach for Q3 since it launched as Talk Radio in 1995.
TalkSport still lags far behind rival BBC Radio 5 Live, which posted a combined reach with sister station 5 Live Sports Extra of 6.43m listeners, up from 6.44m last year. However, 5 Live saw its weekly audience decline from 6.68m last quarter, and its share fell to 4.6% from 4.9% last year and last quarter.
"I'm delighted that we've grown the audience year on year in what is always a difficult quarter for sports broadcasters," said Moz Dee, the programme director for TalkSport.
"Quality sports journalism and continued investment in rights and talent are hitting the right note with existing and new listeners. While these figures only reflect the first few matches of our live and exclusive Rugby World Cup coverage, they seem very promising indeed."
Elsewhere, Global Radio's nationwide Classic FM reached 5.38m listeners in the three months to September 18, down 6.1% on the previous quarter and 5.1% year-on-year.
The Heart network was also down, dropping 4.2% year-on-year to 7.65 million, but the Capital stations were up 2.3% on the previous quarter to 7.03m weekly listeners.
Guardian Media Group's Smooth Radio posted its biggest ever reach of 3.33m, up 9% year-on-year, while Bauer Media's Magic UK was down 3.83% year-on-year to 3.83m.
Overall, RAJAR reported that 90.7% of the UK population tuned in to a radio station every week during the third quarter of 2011, with listening hours up 2% year-on-year.
Listening via digital increased 12% year-on-year in terms of weekly reach in Q3, with 22.8m people now tuning in to radio stations via a digitally-enabled receiver (DAB, online, digital TV and mobile).