Upon completing his sophomore season at the University of Denver, he was quickly signed to a professional contract by the Islanders, who assigned him to play for their American Hockey League (AHL) affiliate, the Bridgeport Sound Tigers.

[6] After making the Islanders' roster to start the 2013–14 season,[1] he scored his first NHL goal on October 8, 2013, against Mike Smith of the Phoenix Coyotes.

[10] Donovan instantly made an impact with the Admirals, leading the club in scoring with 12 points through his first 13 games before he was signed by NHL affiliate, the Nashville Predators, on a two-year, two-way contract on November 4, 2018.

On June 17, 2022, Donovan again left the AHL and signed a one-year contract with German club, Adler Mannheim of the Deutsche Eishockey Liga (DEL).

As a free agent, Donovan returned to North America after securing a one-year AHL contract with the Chicago Wolves on June 14, 2023.

On August 26, 2024, Donovan concluded his 14-year professional career, after he was unveiled as an assistant coach of the Milwaukee Admirals of the AHL, affiliate to former club, the Nashville Predators.