Royle said: "Sam has real talent. He can win a header but more than anything he can control and keep the ball.
"He has a fantastic goalscoring record and has earned the right to step up to this division."
Ipswich chairman David Sheepshanks said: "I view the signing of Sam Parkin as a real coup for the club.
"It's a measure of the esteem in which Joe Royle and the club are held.
"We were particularly keen to sign a younger player of Sam's proven ability but who has the potential to improve to the highest level, hopefully with us."