The 25-year-old former Hibs and Burnley forward is believed to be on Wearside to finalise the deal and a medical is expected to take place today.
Reports suggest the transfer could be worth up to £14m, with a series of performance-related add-ons included in the agreement – a fee which would comfortably outstrip the £9m paid for Hearts’ Craig Gordon and Rangers’ Alan Hutton by Sunderland and Spurs respectively.
Fletcher, who joined Wolves in 2010 from Burnley for £6.5 million, scored 12 Premier League goals last season despite the Molineux club being relegated. He submitted a transfer request earlier this month and Burnley will now be due 15 per cent of the profit Wolves make on the player.
The expected arrival of Fletcher will further strengthen Sunderland manager Martin O’Neill’s striking options following the arrival of former Everton and Manchester United front man Louis Saha last week.
However, despite racking up a series of big-money transfers – Burnley paid Hibs £3m for his services in 2009 – he remains out of favour with Scotland manager Craig Levein with whom there is an ongoing stand-off. Prior to his international exclusion, Fletcher had been capped eight times.