Karl Wilkins Juarno Augustus and Brandon Nansen sported the new green and black kit, which replaces the previous campaign's blue attire.
The range is available to order now from the Saints Store; including training t-shirts, shorts, sweatshirts, hoodies, gilets and bomber jackets.
Saints’ new travel wear collection, which contains polo shirts, quarter zip tops, tracksuit bottoms and jackets, will be released in the coming weeks.
Saints' away jersey for the 2021/22 season – which pays tribute to the thousands of supporters who donated to the club during the pandemic – was also revealed last week.
The new-look home kit is due be released in August.
As for the three new players, Wilkins, Augustus and Nansen, they are all settling in nicely after starting training at Franklin's Gardens last week.
Forwards coach Phil Dowson said: "Karl Wilkins, Brandon Nansen and Juarno Augustus are all here, getting introduced to the squad, finding their way round, trying to learn about 50 names and where everything goes.
"They're all in and getting used to the situation and we're really happy to have those boys on board.
"They're top men and all really keen to get involved.
"Juarno has got a big ball-carrying game, which we've seen with the Stormers, and he's a good athlete.
"Karl Wilkins has come from France and has got a good skillset, great work rate and he's an excellent lineout forward, calling the lineout in Frence. He was captain at Beziers so he's got good leadership qualities.
"Brandon Nansen, looking at some of his games, has real power and ability to get over the gain line and to be really powerful in small spaces. He's also got a good skillset so he'll be able to play the game we want to play.
"They all bring something slightly different but they've all got qualities we're looking forward to seeing in the shirt."