The former Liverpool man was a regular fixture under Mauricio Pochettino last season but struggled to show his best form in the heart of the engine room.
Wijnaldum ended the season with three goals and three assists in 38 appearances across all competitions but only started 18 games in Ligue 1, and he did not play a single minute against Real Madrid in the Champions League last-16.
Wijnaldum was also left out of Christophe Galtier's squad for their pre-season tour of Japan amid speculation surrounding his future and only has two years left to run on his existing Parc des Princes deal.
A return to the Premier League was unsurprisingly mooted for the 31-year-old, who was thought to have been on the radar of Liverpool's fierce Merseyside rivals Everton.
However, Roma have won the race to sign the Netherlands international on loan, which could be converted into a permanent deal at the end of the season.
"It's a really good feeling to be a Roma player. Everyone I have spoken to has given me great feedback about the club and its fans," Wijnaldum told Roma's official media channels.
"The club made it clear just how much they wanted me in the efforts they made to complete the deal, which always gives a player a lot of confidence and belief.
"The reception from the supporters, on social media and elsewhere, has also been fantastic. I promise to give 100% and help the team compete for all our targets this season."
Roma general manager Tiago Pinto added: "Georginio's decision to come to Roma is yet another example of players of the highest level, both in terms of their qualities on the pitch and off it, believing so strongly in the club's plans that they put all their energy into ensuring that negotiations reached a positive outcome.
"We can not be anything other than delighted at his arrival. Gini brings qualities that will further enhance the competitiveness of our squad and a natural leadership that has seen him become captain of one of the best national sides in the world."