The 27-year-old was slated to at least tackle the Indianapolis road course race in May before those plans were scuttled by the COVID-19 pandemic which saw the start of the season delayed until June and travel heavily restricted.
Now, however, he has been locked in for a start in the season finale in a fourth Team Penske entry.
“This is something I haven't stopped thinking about, but I wanted to ensure my focus was on winning our third-straight Supercars championship for DJR Team Penske and all our partners in Australia,” said McLaughlin.
“We are still laser-focused on that and have three more rounds to get it done, but I'm equally as excited to finally get the chance and make my IndyCar debut.
“I've been doing everything I can to keep up with the series this year, from watching as many races as I can on TV to even talking to the drivers and some of the engineers back at the Team Penske shop.
“I never knew if I would be able to get behind the wheel of one of these cars this year due to all the COVID-19 restrictions, but I wanted to be ready if it became an opportunity.”
Said opportunity has arisen, in part, because the Bathurst 1000 will be the final round of the 2020 Virgin Australia Supercars Championship, allowing McLaughlin the time to quarantine upon return to Australia in the likely event that he is still obliged to do so.
Team Penske President Tim Cindric added, “Our plan has always been for Scott to run a race in the IndyCar Series this season, but we never wanted to take the focus away from the main goal, which is winning another Supercars Championship.
“COVID-19 certainly altered those plans early on, but with the way the schedules have lined up at the end of this season, St. Pete became an available option and we remain committed to getting him some IndyCar seat time.
“We know Scott is ready for this challenge and this should add even more excitement to the 2020 season finale in St Petersburg.”
The Kiwi, who already has three IndyCar tests under his belt from earlier in the year as well as the virtual IndyCar series put on before the season proper, will pilot the #3 Chevrolet-powered machine with backing from Shell V-Power Nitro+.
The Grand Prix of St Petersburg will take place on October 23-25 (local time), making for a race start on the Monday morning of October 26 in Australia and New Zealand.