Irfan will replace fellow left-armer Junaid Khan, for the tournament which runs from August 8 to September 16.
The 36-year-old has only played four Tests. He however excelled in the white-ball format, where he has taken 83 wickets in 60 One-Day Internationals and 15 wickets in 20 T20 Internationals.
Tridents open their season on August 12 against Guyana Amazon Warriors.
The Jason Holder-led side will then take on St Lucia Stars at the Daren Sammy Cricket Ground on August 17.
Their next match up will be against Jamaica Tallawahs in Lauderhill, United States before hosting five matches at Kensington Oval in Barbados between August 25 and September 2.
Tridents close out their campaign with fixtures against St Kitts and Nevis Patriots and Trinbago Knight Riders on September 4 and 7 respectively.