Kruger took home the award for her performance in the drama In the Fade, which follows a woman grappling with the aftermath of her family’s death in a bombing.
“Yes she Cannes,” he wrote in the post, including a graphic announcing Kruger as the award’s recipient. “Having witnessed the integrity and dedication that you bring to every job, I’m over the moon to see you getting the recognition you deserve. Only question is what took ’em so long! CONGRATULATIONS, Josh.”
Kruger also reacted to her win on Instagram, snapping a photo of her looking shocked as the award is held up behind her, along with the caption “Wait…….WHAAAAAAAAAAA.”
Kruger, 40, and Jackson, 38, split in July 2016. In a statement to PEOPLE, reps said the two “have decided to separate and remain friends.”
For full coverage of the Cannes Film Festival, including the biggest stars and best red carpet moments, check out people.com/cannes-film-festival
They’ve since remained friendly, stepping out together a month after the split for a stroll in Los Angeles, and then again a few days later, when they were seen hugging at the Los Angeles International Airport.
Jackson has since been spotted getting cozy with a mystery brunette at the Sundance Film Festival earlier this year.
Kruger, meanwhile, has gone public with her romance with Norman Reedus, with the two — who met on the 2015 film Sky — stepping out in New York City in March for a sweet, PDA-filled stroll following repeated sightings together in previous weeks.
Reedus himself also took to Instagram to congratulate Kruger, posting an image of her at the awards ceremony and simply captioning it with an enthusiastic “YESSSSS,” along with heart emojis.