Ian Bell (39), Ravi Bopara (35) and Matt Prior (24) also contributed as the batting attack found some useful pre-tournament form.
No. 2 Pietersen scored 66 off 78 balls to steady the innings after captain Andrew Strauss and Jonathan Trott were both dismissed cheaply. The team was all out in 49.4 overs.
Pakistan opened with Shoaib Akhtar, who bowled Strauss early on but lost much of his menace as the game wore on.