Rivera died in July after drowning during a boating trip at a Southern California lake with her five-year-old son. He was later found safe and well.
Rivera, who played cheerleader Santana Lopez on Glee, would have celebrated her birthday on Tuesday.
Amber Riley portrayed Mercedes Jones on the musical drama. She posted a lengthy message, addressing Rivera with “a little update” and informing her “the earth is REALLY ghetto now!!!”.
Riley added: “Still, I miss you so very much and I wish you were here. There hasn’t been a day where you don’t cross my mind, and when you do, I take a moment of silence to remember all the beautiful moments we got to spend together.
“I’m listening to Amy Winehouse, sippin wine, and eating a very fancy charcuterie in your honour today (don’t worry, I’m checking on mom). HAPPY HEAVENLY BIRTHDAY ANGEL.”
Heather Morris starred as Rivera’s on-screen girlfriend, Brittany Pierce. She posted a black-and-white picture of them together and wrote: “Happy Birthday my angel. I can’t write a sappy monologue because it’s just too hard…but I love you and I can’t describe how much I miss you.”
Chris Colfer, who starred as Kurt Hummel, also posted a picture of himself with Rivera. He wrote in the caption: “Happy birthday, babe. Miss you.
And Kevin McHale, who played Artie Abrams, posted a throwback picture of the Glee cast looking worse for wear while huddled around a birthday cake bearing the message “happy birthday Naya”.
He wrote in the caption: “No one else could get us to be this messy in public.”
Rivera went missing at Lake Piru on July 8th and her body was found on July 13th following an intense search. The Ventura County Medical Examiner’s Office said her death was as a result of accidental drowning.