The 31-year-old joins Vale on a free transfer after his contract with the Saddlers expired at the end of last season.
Page moved for Purkiss after Freddie Veseli failed to accept his offer of a new contract by the club’s June 10 deadline. He will compete with Adam Yates for a place in the team next season.
“We’re extremely pleased to have completed the signing of Ben on a two-year deal,” said Page.
“He is someone that has played to a high level in this league for a few years now and he will really help to strengthen our defence.”
Purkiss, a former Sheffield United trainee, has spent the last three years at Walsall.
He made 39 appearances for the Saddlers last season, including the Johnstone’s Paint Trophy final defeat at Wembley against Bristol City.
The full-back has previously played for York, Oxford, Darlington and Hereford.