The award was voted for by 11 Australian rugby writers over the course of the 2011 Super Rugby season, with one writer each week submitting their 3-2-1 votes for each of the games that an Australian team was involved in.
Genia, who made his Reds debut in 2007, has been an inspirational figure for the Queenslanders so far this term as Ewen McKenzie's men topped the Super Rugby table for the first time since 1999.
The 23-year-old is expected to play a major role in this year's World Cup, as well as the 2013 Lions tour when Britain and Ireland's elite will attempt to reverse the 2-1 series defeat they suffered against the Wallabies a decade ago.
Genia received 20 votes over the course of the 2011 campaign with four man-of-the-match performances against the Stormers, Waratahs, Crusaders and the Chiefs helping him claim the top honour.
Genia and Cooper were level pegging for first place heading into the last round of regular Super 15 action but Genia's outstanding performance against the Chiefs ensured he was crowned the country's best Super 15 player.
Genia's triumph was part of an evening of Reds dominance as they picked up half the gongs on offer at the awards ceremony.
McKenzie lifted the Coach of the Year award for the fourth time, while the Reds were named Team of the Year and were presented with the inaugural Australian Conference trophy after the Super Rugby table was split into three sections.