The 33-year-old has made 113 for the Robins since joining them in 2007 from Parramatta where he made 159 appearances.
Speaking about the annoucement Vella stated “It was a tough decision for me to make. The decision was made for me because I’ve not been offered a new contract, even though I had planned to play another year.
“I felt my body was good enough to play another year but I’m not 25 any more and teams aren’t willing to take a gamble on me.”
Rovers Chairman Neil Hudgell paid tribute to the departing Vella.
“Mick will retire as a modern day legend of the club. He was one of the very first big names to join us in Super League from overseas and in his five years with the club he has been a fantastic leader on the pitch, and a tremendous ambassador for the club off it.
“He can look back on his career with immense pride and I’m certain every single Hull KR fan will acknowledge the massive contribution he has made during his time at Craven Park.
“Everyone at the club wishes him well for his future after rugby, and I’m sure he will get a rousing send off in the final home game of the season against Castleford.”