The Briton will begin his duties at this weekend's Italian Grand Prix when he takes part in Friday's first free practice session for the team.
He will also get further outings over the remainder of the campaign.
Force India team principal Vijay Mallya said: "We worked with him during the Silverstone test (July) and he impressed everyone with his speed and consistency.
"We've always tried to support young drivers and this is a great opportunity for James to gain some valuable experience of driving during Formula 1 race events.
"James will take part in the opening free practice session on Friday (at Monza). He will also run in practice at several other races this year.
"It's always useful to get another driver's feedback on the car and it will help us evaluate James."
Despite his new role in F1, Calado will complete his GP2 campaign with ART Grand Prix. He currently lies fifth overall, having picked up one win and five podiums so far in 2013.
The Force India reserve role has proved to be a valuable stepping-stone for drivers hoping to make a full-time breakthrough in F1.
Nico Hulkenberg, Paul di Resta and Jules Bianchi are currently racing having been third drivers for the Silverstone-based team in the past.