Blackburn bring back Santa Cruz
The 29-year-old Paraguay international returned to Ewood Park after joining Premier League rivals City in a 17.5 million pound deal in 2009.
"Everyone knows what Roque is capable of here and his arrival has already created a real buzz around the place," manager Steve Kean said on the club website.
"We are really looking forward to giving him a platform on which to show his ability."
Santa Cruz scored 29 goals in two seasons at Blackburn, who were taken over by Indian poultry business Venky's last November, but struggled to establish himself at high-flying Manchester City.
"I feel like I am coming home," Santa Cruz said. "This has been the easiest decision of my career.
"I want to get playing and scoring goals again and this is a real chance for me to prove myself after a frustrating period.
"Everyone knows what Blackburn Rovers means to me."