Goodwin and assistant Lee Sharp are now committed until the summer of 2024 with the Paisley club expressing their delight at the deals further aiding their “ambitious plans” for the future.
The pair have helped the side steer clear of the relegation dogfight in the 2020/21 season as they look to be on the cusp of a top-six finish. They also made it to the League Cup semi-final after a famous victory over Rangers in the quarters.
The 39-year-old was backed in the January window with St Mirren shelling out for Scottish international Eamonn Brophy, while the club also promise to get key players on an expiring deals tied up to longer contracts.
Chief executive Tony Fitzpatrick said: "The board has recognised the excellent results and progress this season under Jim and to continue developing as a club we see this as an integral piece of the "plan. Jim has been given one of the highest player budgets of any St Mirren manager and he is now the highest paid manager in club’s history.
The immediate focus will continue to be on Jim leading the team to a potential top six finish. This deal allows everyone to plan longer term to bring further success to our club.
"We are an ambitious club and we believe with Jim ambitions we have an exciting, successfully future ahead."
Goodwin added: "I'm delighted to extend my contract here. I appreciate the board offering the new deal to me and for the recognition of the hard work that myself and my staff are doing here.
"It's a great time to be a part of this club. I feel there is a real air of positivity and we have SMiSA soon to take over the ownership of the club and the introduction of [Paisley-based charity] Kibble which is a fantastic step in the right direction. There are really good people on the board who are as keen as I am to take the club forward and take it to the next level."