The former Swansea City striker traded the Black Cats for Ewood Park on an initial loan deal until the end of the season where he is expected to make his move permanent.
On his arrival at Blackburn, Graham told reporters how he is looking forward to the fresh challenge and hinted it was a big relief to put his Sunderland nightmare behind him.
“It’s been a mad 24 hours," he said. "I was training with Sunderland yesterday morning and then I came down here last night to get things sorted, so I’m delighted to get it done.
"For me to get out of Sunderland and have a fresh challenge is superb for me, so I’m delighted to get it done. I can’t wait to get going and hopefully we can pull together and move up the table.”
Graham, 30, joined Sunderland in the summer of 2013 and oversaw a number of changes at the club.
He arrived at a difficult time at the Stadium of Light, and during his two-and-a-half years on Wearside the relegation-threatened club got through as many as five different managers.
With Jermain Defoe in good form and Steven Fletcher, Dame N’Doye and Fabio Borini providing further attacking options, Graham was always likely to struggle for minutes and it proved so.
He managed just 360 minutes of Premier League action in the first half of the campaign.
He joins a Blackburn side languishing in mid-table and he will be keen to strike up an immediate partnership with fellow forward Jordan Rhodes and help push the club up the table.