A T20 World Cup winner with more than 100 appearances for Sri Lanka in ODIs and 56 IT20 appearances, Perera will bring bags of talent and experience to the Gloucestershire dressing room.
The 28-year old, an aggressive left-handed batsman and skillful right-arm medium-fast bowler, hit the winning runs in the ICC World Twenty20 Final in 2014.
“I am delighted to be joining a talented and ambitious side for the T20 Blast,” said Perera.
“Working alongside two excellent coaches in Richard Dawson and Ian Harvey, I am sure I will learn a lot whilst at the same time adding to the quality already within the group.
“I am hoping to bring a bit of Sri Lankan magic to Bristol and Cheltenham, and look forward to entertaining the crowds.”
“It’s great to have secured the signing of Sri Lankan Thisara Perera for the T20 competition,” said Gloucestershire Head Coach Richard Dawson.
“He’s shown that he is a match winner with both bat and ball, and also brings a lot of experience after playing all around the world. He will be a huge asset to the team and we look forward to him joining us soon.”