"🖤❤️🖤We can’t say the word happy but we’ll say thank you for being a mother & giving me this sweet amazing boy.🖤❤️🖤#mothersday," Dorsey wrote.
The photo shows Rivera smiling wide for the camera while sitting in a restaurant with Josey. The late actress' former Glee co-stars like Jenna Ushkowitz and Heather Morris sent Dorsey their love in the comments.
"This broke me ❤️❤️❤️❤️ I love you," Morris wrote, while Ushkowitz commented with red heart emojis.
A source told ET last month that Rivera and Dorsey's 5-year-old son has "no shortage of love" and is doing really well.
"He’s the sweetest, happiest little boy and there is no shortage of love in his life,” said the source, who added that Dorsey and Josey are "best buds."
According to the source, Dorsey has been lying low and his priorities continue to be Josey and his career. The actor has been working on the show Big Sky. "He’s really proud of this show and the team,” the source said. “It’s been nice for him to have something exciting to put his energy into."
See more on how Rivera's friends and family have been honoring her after her death in the video below.