The TV star, 49, told fans last year that he had been diagnosed with terminal lung cancer and was determined to make the most of any time he had left with his wife Jess and their three sons: Rex, three, and two-year-old twins Rafa and Cormac.
But at the weekend he reunited with fellow presenter Jasmine Harman at A Place In The Sun Live in Manchester.
Sharing a snap on Instagram of the warm clothes he was taking, Irwin told fans: "Selecting wardrobe for @aplaceinthesunofficial LIVE Tomorrow in Manchester. It’s an early start and as I’m not fit enough to run for the train atm I’m prepping the night before.
Watch: A Place In The Sun presenter Jonnie Irwin explains why he kept cancer diagnosis secret
"My wife can’t quite believe it! Cold weather calls for wool, wool, and more wool. It’s also are rare thing for @jasmineharman and myself to both be there on a Sunday so please coming along and we’ll hopefully see you there."
Fans wished the star lots of luck and said they hoped he had a great day.
"You are an inspiration," one posted in the comments section, while another said Irwin was "always inspiring".
"Delighted to hear you're teaming up with your old pal Jasmine for a day of doing what you two do so well, inform educate and entertain," said another.
Several said Irwin and Harman were the "dream team".
Last year, the presenter claimed that he was dropped by the Channel 4 property show after his diagnosis.
Production company Freeform told Yahoo at the time that he was "a hugely important part of the A Place In The Sun family for over 18 years" and that everyone was "deeply saddened" by his diagnosis.
"Much loved by everyone on the production, no stone was left unturned in trying to enable Jonnie to continue his international filming with us during COVID but the production company were unable to secure adequate insurance cover for him," they explained.
"Whilst we were unable to continue to film abroad with him, we’re delighted that he was able to remain as part of our team in the UK for exhibitions. We of course understand how frustrating this must be for him at this incredibly difficult time."