Api Ratuniyarawa has signed a two-year contract extension at Saints.
The Fijian lock has been a big hit since arriving at Northampton from French side Agen in September 2016.
He has played 31 times for Saints, scoring two tries in the process.
Ratuniyarawa has been an increasing influence on the team in recent weeks, starting to cement himself in the second row.
And the 31-year-old is happy to be staying at Saints beyond this summer.
"I'm delighted to be staying here for another two seasons," Ratuniyarawa said.
"I'm happy to sign again and for me coming here, it was with an open mind.
"I wanted to come and learn to be a better rugby player.
"I've found the environment here good. The boys have been really supportive and we've got some good coaches here.
"It's really helped me a lot with my game and that really helped me to make the decision to stay for another two years."