The actress, 37, is engaged to Jaime Lincoln Smith. She revealed the news Sunday on Instagram with a pair of photos showing off her sapphire engagement ring.
“Forever Ever...," she wrote, before sharing a poem.
'Theyll say its love/And they'll know its love/For when they call its name/it will answer to love/Without hesitation' ~me,” she wrote.
The "This Is Us" family was quick to pass along their best wishes to Watson and Smith, who shared the same Instagram post as the actress.
“so happy for you guys, Su!!!!!” Mandy Moore wrote.
“So beautiful! So happy for you both,” Melanie Liburd, who plays Beth's cousin, Zoe, on the hit NBC drama, wrote.
“Ahhhhh!!!! Congratulations lovely!!! So happy for you guys!!” commented Chrishell Hartley, who’s married to Watson's co-star Justin Hartley.
Smith is also an actor, having appeared on "New Amsterdam," "NCIS: New Orleans," "Blue Bloods" and “The Deuce.”
Watson is certainly keeping busy these days. In addition to planning a wedding, she has the fourth season of "This Is Us" kicking off on Sept. 24 and she stars alongside Tom Hanks in the Mister Rogers biopic, "A Beautiful Day in the Neighborhood," due out Nov. 22.