Speaking to the Official Club Website, Keane said: "I truly believe that I am joining a Club that has the potential, ambition and infrastructure to once again be a Premier League side.
"The Club's owner and Chief Executive impressed upon me their total focus on achieving this quest at the earliest opportunity and I can't wait to get started."
A press conference is to be held at 4pm to unveil the former Glasgow Celtic, Manchester United at Nottingham Forest midfielder as Town's new boss.