After making his NRL debut in Round 3 last year, Seumanufagai has since played 34 NRL games and has become a key member of the Wests Tigers forward pack.
The 23-year-old said the new deal was a boost leading into the back end of the year as the Club pushes for a place in the finals series.
"I'm really excited to stay with the Wests Tigers," Seumanufagai said. "I'm happy that my contract is sorted for next year and grateful for the opportunity."
"I was lucky enough to get my first shot at NRL last year, and whilst it was tough in terms of results, I felt that I took a lot out of it and it made me stronger for this season.
"It's really exciting to be part of the younger group of players at the Club and I think we can achieve something special in the next few years.
"For now though, it's all about a strong finish to the year and we are focussed on making a run to the finals."
Hailing from Wellington in New Zealand, Seumanufagai played his junior football for the Wainuiomata Lions, and later the Hills Bulls, before being recruited to the Parramatta Eels junior system.
Seumanufagai joined the Wests Tigers in 2012, playing in the NSW Cup Grand Final later that year with Balmain Ryde-Eastwood.
Head Coach Mick Potter expressed his delight in securing the hard-working prop for another season.
"Ava has steadily improved as the year has gone on," Potter said. "There's no doubt he has been a real asset for us with his metres after contact, ability to build ruck speed and exceptional defence."
"Ava has worked really hard on his fitness at every possible opportunity and it's showing in his football as he starts to get more and more minutes.
"Defensively Ava is rock-solid and it's a pleasing aspect because he has developed that and worked really hard in the pre-season to get where he is at now.
"The players love it when Ava comes on the field, he gives us that lift and really deserves what he is getting."
The announcement comes on the back of fellow young forward Sitaleki Akauola extending his time at the Club for another two years just yesterday.Like