Lay, 30, whose previous Super Rugby has been played for the Blues, is in his debut season with Moana Pasifika.
He made his first-class debut for Auckland in 2016 but has also played 20 games for Bay of Plenty and had a season for Bristol Bears in 2018-19. He has played 12 Tests for Samoa since 2017.
Lay said it was an honour to lead the side and was grateful for the backing of Christian Lealiifano, Sekope Kepu and Solomone Funake, who have all been leaders of the side.
"I'm lucky that I've got a good leadership group around me with plenty of experience. I've been impressed with how they're leading the team. I can take a step back and allow them to deliver key messages.
"I got some nice personal messages from the boys in that group, and they said they've got my back no matter what. They're here to support me with whatever we need."
Lay said they wanted to put in performances their people could be proud of as a team. They want their fans to look up to them and get behind them and what they are trying to achieve.
"For me, I just need to focus on being the best version of myself, and hopefully, the others will follow."
Head coach Fa'alogo Tana Umaga said Lay had earned respect from his players.
"James is a hard worker, and he leads through his actions as much as he leads through his words. The way he plays, he doesn't cut corners and showcases all the values that this team is about.
"He was a stand out choice, and we had a lot of choices in this group. He's not one that leads because he wants to be seen or know, but he leads because that's his nature."
