Harry is in town for the Invictus Games, where Markle was spotted showing support for the British royal, and reportedly kept a low-profile on the set of the series.
“He was super low-key, met some crew and was so happy to watch his lady,” a source told Hello! magazine.
“He’s incredibly supportive of her work.”
Markle, who plays Rachel Zane on the series, showed her boyfriend around the set, according to the publication.
On Sept. 23, Markle was spotted in the audience for the opening night of the Games. Harry created the Invictus Games after he served as an officer in Afghanistan in 2008.
The couple was not seated together during the ceremony; instead, Harry sat in a VIP section next to first lady Melania Trump and near Canadian Prime Minister Justin Trudeau.
The prince is expected to remain in Toronto until Saturday, Sept. 30.