Markelov is one of the most experienced Formula 2 drivers, having joined the series in 2014 when it was called GP2.
The Russian driver picked up nine wins and a further eight podiums in his five years in the championship, competing for Russian TIme.
“I am very happy to join MP Motorsport at Monaco”, said Markelov.
“Monaco is a special place, and I can’t think of a better occasion for a one-off return to Formula 2. I’m looking forward to meeting lots of old friends, and of course wish Jordan all the best in his effort to win the Indy 500!”
MP’s team principal Sander Dorsman added: “We can’t think of a quicker man to step into Jordan’s car at Monaco than Artem. We are sorry to lose Jordan for the weekend, but Artem is a worthy replacement.
"I look forward to working with him during an important weekend for us and hope that he will help us to a pair of great results at Monaco.”
King will make his 2019 IndyCar debut next weekend at the Indy 500, provided he isn't one of the three drivers that's bumped from the event on Sunday.
Markelov is currently competing in the Japanese Super Formula championship and finished tenth on his debut at Suzuka last month.
Bahrain International Circuit - Winter testing
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