Officials at Britain's department of prisons did not immediately respond to requests for comment on the subject.
Fielder-Civil was found guilty of beating up pub manager James King in a barroom fight in 2006 and then offering him a bribe to keep quiet about it. Fielder-Civil, 26, was arrested a year ago and was less than halfway through a 27-month sentence for assault and obstruction of justice.
The Daily Mail newspaper said Fielder-Civil walked out of Edmunds Hill Prison in eastern England wearing jeans, a striped red shirt and a trilby hat. Winehouse, who has repeatedly appealed to concert audiences for the release of "my Blake," was not there to see him, the paper said. The newspaper did not offer a source for its information.
Winehouse shot to stardom off the release of her multiple Grammy-winning album "Back to Black" in 2006. But her music has struggled to command as much attention as her personal life. British tabloids publish constant reports on Winehouse's alleged drug use, her run-ins with the law and her chaotic relationship with Fielder-Civil.
Winehouse herself went into rehab earlier this year after The Sun tabloid published a video apparently showing the singer smoking crack cocaine.
On Friday, the couple who sold the video footage of Winehouse to the newspaper pleaded guilty to drug charges. They are due to be sentenced later this month.