Frittelli turned professional after the 2012 NCAA Championship and played on the European Tour via sponsors exemptions for the rest of the year. He started 2013 with a second-place finish in the Telkom PGA Championship behind Jaco van Zyl. He played most of the year on the Challenge Tour, winning his first tour event at the Kärnten Golf Open in June.[4]
Frittelli's performances in early 2013 lifted him into the world top-300 but he then had two years of poor performances, dropping to 926 in the world rankings. He showed a return to form when losing a playoff for the Australian PGA Championship in late 2015.[5] 2016 was a successful year with second place in the Golden Pilsener Zimbabwe Open, a tie for second in the Tayto Northern Ireland Open and then a second win on the Challenge Tour in the Rolex Trophy. He finished 8th in the Race to Oman rankings to earn a place on the 2017 European Tour.
In 2018, Frittelli played some PGA Tour events because of sponsor's exemptions and his world ranking.[6] He earned enough points to qualify for the Web.com Tour Finals.[7] At the Web.com Tour Finals, he secured his PGA Tour card for the 2018–19 season.
After finishing 172nd on the 2023 FedEx Cup rankings and losing his playing rights on the PGA Tour, Frittelli gained entry to the 2024 European Tour, through a new exemption category (for players in positions 126-200 on the PGA Tour rankings the year before) and won the 2024 Bahrain Championship, his first European Tour victory in six years.[9]