The 23-year-old, who was the Shrimps' top scorer last season, will now remain at the Globe Arena until the end of the 2015-16 season.
Redshaw has been with Morecambe since January 2012 was linked with a move away from the club in the summer before a serious hip injury saw him sidelined up until November.
"This is fantastic news for the club," boss Jim Bentley told the club's official website.
"Jack showed us all what he is capable of last season with his goals and he will only get better.
"He is still only young but he's a great lead who works tremendously hard at his game and is also getting stronger all the time.
"This is a massive boost for the club, the supporters and me as it helps my plans for the future."
- Sports & Recreation