The England Under-20 internationals, who are all part of the club's academy system, have played for Exeter and in the Championship with either Plymouth Albion or the Cornish Pirates this season to boost their development.
"We're big believers in our academy system and the quality that's coming through there. We're also big believers in these guys as individuals," Chiefs boss Rob Baxter told the club's official website.
"It's a really nice boost to know they're around for the next couple of years and we can work closely with them to help them develop into Premiership players.
"They are probably the most enjoyable guys to sign on because they have been part of the club's structure for a long time and they represent the future of the club."