The latest branch of the ever-expanding Canadian coffee and donut chain, which is based at the Meadow Retail Park on Meadow Lane, will officially open to the public on June 30.
The store, which will seat up to 100 guests, will also provide a drive-thru and takeaway service, as well as a delivery service.
The first guest in the drive-thru and the restaurant will win free drinks for a year, a prize the chain says is worth £3,100.
It will also give away a free breakfast meal to its first 100 customers.
Free drinks and donuts will also be given to those who activate a Tim Hortons digital wallet.
The new restaurant will open every day from 6am until midnight.
Kevin Hydes, chief commercial officer of Tim Hortons franchise in the UK said: “Portadown is a major town with great transport links and has a wonderful community so we look forward to opening our doors here at the end of June.”