Midfielder Gilligan has become a mainstay since he was signed as a teenager by Colin Calderwood and has played in a variety of positions during his stay at Sixfields.
"Ryan is only 23 years old and to be on the verge of making his 200th appearance for the club is a great achievement," Cobblers manager Ian Sampson told the club's official website.
"He does a good job for the team and he is well worth those 200 games.
"I think Ryan is the type of player every team needs, he's very unselfish, can play in lots of different positions and he is a real team player.
"It's been well-documented that he's got a bit of extra bone growth on his ankle but that will be rectified in the summer."
Source: PA
Source: PA