The nationally contracted trio of Cian Healy, Rob Kearney and Mike Ross have already confirmed new contracts and the addition of Newcastle Falcons out-half Jimmy Gopperth and Ireland lock Mike McCarthy will add experience and quality to the squad.
The province also hopes to agree a deal for one more overseas player in the coming weeks.
With forward duo Healy and McCarthy having both agreed three-year deals, in all 16 players have extended their contracts by two years.
Of the overall tally, 16 players are recent graduates from the Leinster Academy including three props, Jack McGrath, Martin Moore and Jack O'Connell, who will compete alongside Michael Bent who linked up with Joe Schmidt's side earlier in the campaign.
In a further boost, in a little over two weeks since applications opened, almost 10,000 Leinster Season Ticket holders have already renewed their places for next season. Season tickets will go on public sale from next Wednesday online here.
Commenting on the contract extensions and the newcomers for next season, Leinster head coach Joe Schmidt said: "Ahead of a few big weeks for us in both the PRO12 and the Amlin Challenge Cup, it's great to have confirmation that so many of our current squad are staying with us, along with a few new players that will add further value to what we believe is a really competitive squad.
"The players have done a great job in recent years and they're committed to maintaining that in the seasons to come but, in the short term, our focus will be on Ulster this weekend and London Wasps the week after."
NEW LEINSTER CONTRACTS:
3 Years - Cian Healy (national contract), Mike McCarthy
2 Years - John Cooney, Sean Cronin, Luke Fitzgerald, Jimmy Gopperth, Rob Kearney (national contract), Brendan Macken, Ben Marshall, Fergus McFadden, Jack McGrath, Jordi Murphy, Eoin O'Malley, Mike Ross (national contract), Quinn Roux, Dominic Ryan, Richardt Strauss, Devin Toner
1 Year - Leo Cullen, Darren Hudson, Martin Moore, Jack O'Connell, Noel Reid