Pietersen was left out of the ongoing third Investec Test after his contract wrangles with the England and Wales Cricket Board were complicated by the text messages he sent to opposition players during the drawn match against South Africa at Headingley.
A Surrey spokesman said: "He is available. He will be in the squad."
He was ruled unavailable for Surrey's LV= County Championship match at home to Middlesex, which started on Wednesday, and reportedly went on a short holiday abroad with his family.
The mercurial South Africa-born batsman has apologised to England for the texts, without divulging their specific content, and it is thought his international career will remain on hold until negotiations with the ECB are concluded.