Props Donald Brighouse and Hisa Sasagi, and fullback Michael Collins, have all signed through to the end of the 2019 season, while winger Mitchell Scott has signed for this season.
Brighouse (25) and Sasagi (30) have both been selected for Super Rugby sides in the past few seasons and were a couple of powerful tighthead props for the Otago team last year.
The Otago scrum was in menacing form last year and right through the regular season had a 100% success rate.
Sasagi and Brighouse shared time in the front row and played well. They both went on the Samoan tour to the northern hemisphere last year.
Sasagi was picked for the Hurricanes in 2016 but did not take the field because of injury.
Brighouse, a former New Zealand Colt, made his debut in Super Rugby earlier this month, turning out for the Crusaders as a replacement off the bench in a win over the Jaguares.
He was back playing for the Dunedin club on Saturday.
Scott (27) played his blazer game for Otago last season and has been a steadying influence for Otago.
He had previously played for Tasman and the Western Force before turning up in Dunedin a couple of years ago.
Collins (24) made his debut for Otago in 2012, a year after leaving Otago Boys' High School, and he has played 43 matches for Otago.
Collins did not play for Otago last year because of a leg injury.
He started playing in the midfield for Otago but moved to fullback in 2016 and has found success there.
He was signed for the Blues last year but will not play for the Blues side against the Highlanders this Friday because of a hand injury.
Otago Rugby Football Union general manager Richard Kinley said it was a great move to secure the players for the coming season.
They were experienced players who had performed at a provincial level.
He said there were about another half dozen players to sign contract for the coming year.
The union wanted to sign players from the club competition but if the depth was not there other options may be looked at.
