Saracens captain Steve Borthwick, scrum-half Neil de Kock and Scotland international Kelly Brown have agreed contract extensions with the Premiership champions.
Sarries have also signed Cambridge's Ben Spencer, with the length of the deals so far undisclosed.
Second row forward Borthwick, 31, who has 57 England caps, joined the London club from Bath in 2008.
Back row forward Brown, 29, arrived from Glasgow Warriors in January 2010.
And 10-time South Africa cap de Kock, 32, has made 126 Sarries appearances since joining from Western Province in 2006.
"There is a fantastic group of people who work hard for each other," Borthwick told the club website.
"People talk about Saracens as a special club, and they are right in many ways.
"We have a long way to go in many respects, and I'm looking forward to the journey."
Meanwhile, 19-year-old scrum-half Spencer arrives after impressing in a pre-season friendly for Sarries.
He joined Cambridge from Ivy Bridge Community College last summer and went on to play 29 times in National League One.
"I was looking forward to another season at Cambridge, and it's completely beyond my expectations to be signing for the champions," he said.
"There is a real determination around the club to work unbelievably hard, and retain the Premiership title, and I'm determined to play my part."