Miniclip.com has 3.2 million UK unique users according to ComScore and is ranked first on Google for the search term "games".
SunChaser will take over the account on 1 February, adding Miniclip to the two other publishers it represents, The Student Room and Justin.tv.
The sales house launched in the summer with a stated aim of representing no more than five publishers at a time.
Pieter Kooyman, director of advertising at Miniclip, said: "The team at SunChaser impressed us with their passion for our business and their idea for the evolution of our ad products.
"We'll be supporting their team with fantastic new opportunities, in-depth research, and continued investment in the site."
This article was first published on mediaweek.co.uk