Sterling K. Brown officially joins 'Marvelous Mrs. Maisel' following Rachel Brosnahan's request

It's official... Sterling K. Brown is joining another popular TV series!

The This Is Us star announced in an Instagram video on Monday that he will play a role in season three of Amazon's The Marvelous Mrs. Maisel.

"I'm Eastward bound. I'm going to do a little TV show. Maybe you've heard of it? The Marvelous Mrs. Maisel," he exclaimed. "The Palladinos were kind enough to write a little something for your boy and I said yes. So, stay tuned. I'm getting together with Midge and it's going to be awesome."

"I'm beyond excited to share some pretty marvelous news," he added in the caption. "#MrsMaisel, I'm coming for you!"

The show's star, Rachel Brosnahan, told ET last month at PaleyFest that Brown, who was her ultimate dream guest, was "in negotiations" to join the cast for the upcoming third season. What type of role did she think he could play?

"I feel like I'm not allowed to have any opinions about the show," she replied. "Our writers are good here, and they would come up with something brilliant, I'm sure."

Creator Amy Sherman-Palladino also weighed in on having Brown join the cast, telling ET, "[Brosnahan] doesn't have to campaign very hard. We all want Sterling K. Brown on the show."

"We're massive fans, and we just love him to death, so we would be thrilled," she added. "Thrilled, thrilled, thrilled."

After Brosnahan initially pitched the idea to ET at the SAG Awards in January to have Brown join her show, the 43-year-old actor told us he'd totally be down for it.

"I would go crazy," he said at the time. "I'm in, I'm in."

"The show is done at such an incredibly high level," he continued. "It's so funny, and it's so full of heart. It's so specific. Like, I love the specificity of the world, and I would love to step in that. The Palladinos are so clear in what they're doing. You know, that's the type of people you want to work with."

Hear more in the video below.