Its share rose from 42.9 per cent in the second quarter to 43.6 per cent. Digital radio was identified as a key factor, with 65 per cent of digital listening shared by commercial channels.
In London, Heart 106.2, the Chrysalis-owned station, regained the top spot among commercial stations by overtaking Emap's Magic 105.4.
Heart's share remained unchanged from the second quarter at 6.1 per cent, while Magic's dropped from 6.5 per cent to 5.3 per cent. Capital's share continued to fall, from 5 per cent to 4.7 per cent.
Richard Huntingford, the chief executive of Chrysalis Group, said: "I'm delighted that we have achieved our target of becoming London's most listened to breakfast show with Jamie [Theakston] and Harriet [Scott], and that we also performed well across the rest of the schedule at Heart 106.2."