O'Connell's show now draws 258,000 listeners in London, according to the figures for the three months to September.
The boost sees the show up from the 221,000 recorded for the second quarter, showing a remarkable recovery by O'Connell after he slipped down to 13 earlier in the year.
The latest good news tops a good year for the show, which won the Gold Award for best breakfast music show in the Sony Radio Academy Awards in May. In June, O'Connell signed up to front the show for another two years until 2005.
The success of the show contributed to a good set of results for the station, which has seen it post a record market share of 2.1% in London, with 502,000 listeners tuning into its mix of alternative dance and rock music, and light-hearted presenting style.
The latest Rajars are the second in which the station has posted national figures, since it went digital earlier in the year. The station has 634,000 national listeners, up from 602,000 last time, and a share of 0.5%.
Xfm's Zoe Ball's drivetime show was another success for the station. It added 78,000 listeners, bring its total to 240,000 in London.
Ball, who in August signed a contract with the station for another year, is to find herself competing against her friend Sara Cox, who is moving from the Radio 1 breakfast show in January after her audience went into steep decline.
This quarter, Cox's breakfast show lost another 25,000 listeners in London and 134,000 overall, a less dramatic loss than the 474,000 who tuned out last quarter nationwide, with almost half of them from London.
Cox makes way for Chris Moyles, who will compete against O'Connell and Johnny Vaughan when he takes over from Chris Tarrant on Xfm's sister station Capital Radio next spring.
Vaughan will be charged with the Herculean task of retaining the 1.2m listeners who tune into Tarrant every weekday morning.
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