Pietersen has not played cricket since pulling out of the Auckland Test against New Zealand in March with bone bruising behind his right knee - an injury he first suffered during a training week in Queenstown before that three-match series.
After a repeat scan on the injury, Pietersen was last month ruled out of the Champions Trophy.
But in a Twitter interaction, he was asked by a follower if he will be playing at Headingley, and replied: "YES I AM!"
Surrey will not officially announce their team until Thursday.
But as long as Pietersen does take part, he will then have a second opportunity - for England against Essex at Chelmsford - for match action before the five-Test series against Australia.
England have always been confident that the batsman will be fit to play in the first Ashes which starts at Trent Bridge on July 10.
That means one of the current incumbents - probably Jonny Bairstow but possibly Nick Compton - would have to give way.