The Carrickfergus man was left dejected on Saturday when he came off his Honda Racing Fireblade on the penultimate lap, causing the race to be stopped.
Irwin was in third place at the time and on course to return to the rostrum when the incident occurred, leaving his Honda destroyed.
Fortunately, the 31-year-old escaped unhurt, and Irwin bounced back to seal third place behind McAMS Yamaha riders Jason O’Halloran and Tarran Mackenzie.
“The team gave me a great bike and I tried to go with Jason (O’Halloran), and I tried to do that without using too much rear tyre,” Irwin said.
“When the guys behind caught me I started to have a few front-end moments, but I could quickly see that I had a lot more rear tyre than them. Bradley (Ray) and Ryan (Vickers) were really struggling with the tyre, as was Taz (Tarran Mackenzie), but my bike had a bit of grip to recover the positions and I also had a great set-up from the team.
“Hats off to Honda because it was a brand new bike they built me for today after I destroyed it yesterday. I got away very lightly but the bike was snapped – the tank survived but I think that was about it.
“All my sponsors and team sponsors deserve this podium.”
Irwin – sixth in race three – is now up to 10th in the standings after four rounds, and is only seven points outside the top-eight Showdown places.
His brother Andrew finished 11th in Saturday’s race and was eighth and fifth on Sunday on the SYNETIQ BMW.
Aussie O’Halloran has taken over the title lead following a hat-trick of victories, beating pervious championship pacesetter Christian Iddon (VisionTrack Ducati) in the first race. Iddon lost ground when he crashed out as he battled for third with Lee Jackson on lap 10 in race two.
O’Halloran completed his hat-trick when he held off Danny Buchan (SYNETIQ BMW) in race three, with Iddon ninth. Reigning champion Josh Brookes’ woes continued as he as finished 17th, 16th and 14th in the three races.
Dungannon teenager Cameron Dawson was celebrating a double as he won both British Junior Supersport races, while James McManus finished fourth in race two.
In the British Talent Cup race, Jamie Lyons sealed the runner-up spot on Saturday. Race two was cancelled.
Eugene McManus was ninth in the National Junior Superstock race, with Simon Reid 12th.
Keith Farmer, 11th in the opening National Superstock 1000 race, was disqualified from race two following a post-race technical inspection of his Morello IMR Kawasaki.
In the British Supersport class, Lee Johnston finished second in Saturday’s Sprint race on the Ashcourt Yamaha but crashed out of Sunday’s race in tricky conditions.
Korie McGreevy, fourth on Saturday, was also caught out by the conditions in race two on the Mar-Train Yamaha.
Gearlink Kawasaki’s Eunan McGlinchey was sixth and fifth.
Round five is at Donington Park National from August 13-15.