The experienced quartet have been deemed surplus to requirements by new boss Kenny Jackett as he prepares for life in the third tier.
Wolves have suffered back-to-back relegations over the past two seasons and are determined to stop the rot under Jackett.
Midfielder Henry has been with Wolves for the past seven seasons and has made over 250 appearances for the club, while O'Hara arrived from Portsmouth in a £5million deal in June 2011.
Defensive duo Ward and Johnson have also been informed they can head for pastures new, with Johnson having cost £7million from Birmingham two years ago, while Ward has been at Molineux since January 2007.
A statement on the club's official website read: "As a starting point to a reshaped squad, Wolves have confirmed that Karl Henry, Stephen Ward, Jamie O'Hara and Roger Johnson have officially been made available for transfer.
"Following the squad's return to pre-season training this morning, head coach Kenny Jackett spoke individually to the four players to inform them of his decision.
"Conversations had already taken place with the players' agents throughout the close season as Wolves prepare for the League One campaign."