Rivera’s body was recovered from Lake Piru on Monday, five days after the 33-year-old was reported missing following a boat ride.
Riley, 34, chose to pay her respects by remembering Rivera singing Skidamarink with Josey.
She captioned the post: “My favourite duet partner. I love you. I miss you. I don’t have words right now, just lots of feelings.
“Rest In Peace angel, and know that your family will never have to worry about anything.”
Riley was one of many of Rivera’s former colleagues who bound together in solidarity after it was announced yesterday that a body had been found in the ongoing search for the star – with Heather Morris, Chris Colfer and Kevin McHale pictured holding hands as they awaited further information.
Several other Glee stars have since paid tribute after the tragic news.
Lea Michele, who played Rachel Berry in the hit musical comedy series, posted a picture of both Rivera and Corey Monteith on her Instagram story, with Monteith having died of a drug overdose six years earlier.
Jane Lynch, who played fearsome gym coach Sue Sylvester in Glee, paid tribute on Twitter, writing: “Rest sweet, Naya. What a force you were. Love and peace to your family.”
Colfer, who played Kurt Hummel in the series, wrote on Instagram: “How can you summarise a decade of friendship and laughter with words alone? If you were friends with Naya Rivera, you simply can’t.
“She spoke truth to power with poise and fearlessness. She could turn a bad day into a great day with a single remark.
“She inspired and uplifted people without trying.”