Watford have agreed fees with Tottenham to sign their French midfielders Etienne Capoue and Benjamin Stambouli.
Arsenal striker Lukas Podolski will complete his transfer to Galatasaray on Saturday afternoon.
Goodwillie, whose last appearance for Rovers came on the final day of the 2012/13 season, had one year remaining on his contract but has recently been linked with a move to Kilmarnock.
The 25-year-old was signed by Steve Kean in August 2011 from Dundee United for a fee in the region of £3million.
But during his stay at Ewood Park he made just 34 appearances - 10 starts - for the club, scoring five goals, and was sent out on loan to Crystal Palace, Dundee United and Blackpool.
A Rovers statement read: "Blackburn Rovers Football Club and David Goodwillie confirm the player's departure from the club by mutual agreement.
"The club thanks David for his work and dedication during his time at Ewood Park and wishes him all the best for the future."