New RAJAR figures show that the DJ's average weekly audience in the three months to September 16, 2012 was 6.73 million listeners - its lowest audience since 2006.
In the third quarter of 2012, Moyles was beaten by Radio 4's Today programme by an average of 200,000.
The long-running current affairs show featuring John Humphrys and Evan Davis attracted an average weekly audience of 6.94m during the period.
For Radio 1, it was a further slump compared to the figures of the second quarter of 2012, when the listenership came to 6.93m.
Overall, while Radio 1's average weekly reach was down 5.5% year-on-year to 11.19 million, Radio 4 pulled in 10.85 million listeners weekly, up 2.7% year-on-year.
Photo gallery - Chris Moyles's career in pictures:
Copyright: Rex FeaturesDuring his last show, Moyles told the listeners: "I've had the best time ever, I've had a few lows, but mainly a gazillion highs doing this show. It has been my dream doing it, and has been so much better than it could be.
"It's been awesome. Thanks to the team who've been great, and the listeners who are more than just people that listen to the show."
Moyles, who hosted his final breakfast show on September 14, was replaced by Nick Grimshaw.
Grimshaw has received the backing of a number of his Radio 1 colleagues, such as Zane Lowe, Greg James and Scott Mills.
Watch the last segment of the Chris Moyles Radio 1 breakfast show below: