Hosts South Africa, who reached the final by defeating Argentina 35-3 on Sunday, have Shaun Adendorff and Jan Serfontein nominated with JJ Hanrahan from Ireland completing the outstanding trio.
The shortlist represents the voting of team managers, match officials and media at the tournament.
For the first time, the public now has the chance to vote on this shortlist on the official Facebook page www.facebook.com/irbjuniorworldrugby.
The results of the public poll will be considered, along with the original votes, when finalising the winner.
IRB Vice Chairman Oregan Hoskins said: "We have enjoyed some wonderful individual performances at this tournament and some memorable matches.
"The skill levels, passion and dedication of the future stars of rugby on show in Cape Town during the past three weeks have been breathtaking.
"I send my warmest congratulations to the three nominees who have contributed to an outstanding event, and wish all the players well for the final round of matches on Friday."
JJ Hanrahan (Ireland):
A first nomination for Ireland in this award, the 19-year-old returned for his second Junior World Championship and opened his 2012 account with a 13-point haul against South Africa in Pool B.
Hanrahan switched to out-half for the tournament after playing centre in the Under-20 Six Nations, when captain Paddy Jackson did not travel, and he has been the driving force in the Irish team often controlling the tempo of the game.
An exceptional kicker, possessing maturity and vision with his tactical kicking game, he is the joint second highest points scorer at the 2012 Junior World Championship.
One key reason that Ireland have already guaranteed their best ever JWC finish is the excellent relationship he has formed with his half-back partner Kieran Marmion.
Vote online now for JJ Hanrahan - www.facebook.com/irbjuniorworldrugby.