The business purchased the listed building for around £800,000; almost double its asking price.
The former place of worship was deconsecrated in 2010, and has a very distinctive tower as part of its structure.
Wetherspoon chairman Tim Martin, who grew up in Northern Ireland, told Premier: "We are confident that a Wetherspoon pub will be good for the city and also act as a catalyst for other businesses to invest in Belfast.
"We are doing very, very well... and that gives us confidence to have a look at a few more areas.
"I think it's because we have a lot of people who have been working for us now for a long time, and they are very good."
This is the second church in the last year in Belfast to be bought and converted into a business.
Ulsterville Presbyterian Church, a Grade B listed building, was made into a restaurant for £2.2 million.