Strootman was joined at PSV with fellow Utrecht recruit Dries Mertens. He said about the move, "I could have continued my development at Utrecht, but PSV is one of the top clubs in Holland, where I can quickly become a better player. This was the most logical step. There have been a number of steps in quick succession, but I do not think about it."  Strootman made his PSV debut in a 3–1 home win against AZ. He made 88 total appearances for the Eindhoven club.
On , PSV and Roma finalized a deal for Strootman's transfer to the Italian Serie A side in a deal worth €17 million, with the fee potentially rising to €19 million through add-ons. He was given the number 6 shirt. After completing the move, Strootman commented to the Gazzetta dello Sport, "I'm really happy to be here. The negotiations went on too long, but I'm finally a Roma player. This is a top club, I joined because I know we can start winning immediately."  In a pre-season friendly against the Major League Soccer (MLS) All-Stars, Strootman scored one goal — in the fifth minute — and assisted another as Roma prevailed 3–1 at Sporting Park, Kansas City, Kansas. He scored his first goal for Roma in 3–1 victory over Parma. He scored also in two draws, against Torino and Atalanta. Both games finished 1–1.
Strootman is said to be a tough-tackling midfielder, possessing good vision and balance on the ball. He is a physical, tactical strong midfielder. He is best used as a central midfielder, often serving as a box-to-box midfielder or a deep-lying playmaker. He is known as the DutchRoy Keane, drawing comparisons for the uncompromising style of play.