Sali Mali and her mischievous friend, Jack Daw
The former Catatonia singer, who announced the band's split in September, was in Cardiff to record the theme tune to a hit animated series called Sali Mali, aimed at three-year-olds.
Matthews has been spending time away from the spotlight.
A spokeswoman said the singer was currently thinking about what direction she wanted to take her career in.
Matthews has undergone treatment for asthma, but media reports have continually linked her ill health to her party lifestyle.
The spokeswoman cautioned that the Sali Mali recording session in Cardiff should not be seen as a return to do more recording work by Matthews.
The 32-year-old singer was reportedly delighted, though, to be involved in the Sali Mali project, which she connected with.
"It was a nice session and it was good to see her back, she is quite a character to have here."
Matthews grew up with tales from the Sali Mali storybooks, which has now become an animated series and is broadcast on Nickelodeon and the S4C Welsh language channel.
The series is narrated by Notting Hill star Rhys Ifans.
Siriol Productions, who make the series, hope to emulate the success of Superted, a previous Bafta award-winning hit for the studios.
The singer spent an hour recording three versions of the song and was reported to have enjoyed the recording session.
"Cerys was keen to do it and I think she enjoyed it very much," said Robin Lyons, managing director of Siriol Productions.
"I also think Cerys is not really a here-today, gone-tomorrow type of performer and I see her doing all sorts of things in her career."
The stories feature a Welsh mam and her mischievous bird called Jack Daw, the naughtiest bird in Wales.
Sali Mali is now attracting fans as far away as Korea and Australia.
A second series of 26, five-minute episodes of Sali Mali is due to be broadcast on S4C and Nickelodeon in the new year.