And England international Owen Farrell has also been recognised by his peers, winning the young player award.
New Zealander Evans admitted he was "surprised and humbled" to land the Rugby Players' Association headline honour at their annual awards evening in London.
The former All Blacks number 10 joined Quins from Auckland Blues in 2008 and he has been unquestionably their most consistent player during that time.
His goalkicking and masterful tactical play has helped guide Quins into their first Premiership final at Twickenham, having finished top following the 22-game regular league campaign.
Quins and England captain Chris Robshaw was runner-up to Evans, with Northampton centre George Pisi third.
"I was very surprised and humbled to win this award," Evans said. "It is a great honour to be voted for by your fellow professionals. Just to be nominated was a huge honour in itself."
Saracens fly-half Farrell, meanwhile, added the RPA award to his Premiership young player trophy earlier this month, completing a memorable season when he also gained international honours for the first time.
"It is a massive honour just to be nominated, never mind win this award, especially as it is voted for by your fellow professionals," Farrell said. "These are the guys you play against week in, week out and all you want to do is earn their respect."
Gloucester backs Jonny May and Freddie Burns finished second and third, respectively, behind 20-year-old Farrell, while 2003 England World Cup winner Jason Robinson was inducted into the RPA hall of fame.