Rivera, 33, went missing during a boating trip with her four-year-old son on a lake in California on July 8.
Five days later, following a major search effort, her body was retrieved from Lake Piru.
An autopsy found that she had drowned in a tragic accident, the Ventura County’s Medical Examiner confirmed on Tuesday.
Tributes have continued to pour in for Rivera, who was best known for playing cheerleader Santana Lopez on Glee from 2009-2015.
The musical-comedy show’s creators, Ryan Murphy, Ian Brennan and Brad Falchuk, shared a joint message, praising her work on the show and saying she was a “joy to write for, a joy to direct and a joy to be around”.
Her portrayal of Santana, an openly LGBT character who proved hugely popular with fans, was described as groundbreaking.
The creators said: “It was one of the first times an openly lesbian, high school relationship was seen on network television and Naya understood what ‘Brittana’ meant to the many young women who were seeing themselves represented on television for the first time.
“Naya always made sure that Santana’s love for Brittany was expressed with dignity, strength and with pure intentions. Naya was always moved by the girls who reached out to her to tell her how much Santana and Brittany’s love affected them.
“Naya’s obligation to them – and to all of her fans – was obvious. She had the rare combination of humility and endless confidence in her talent.”
Murphy, Brennan and Falchuk said Rivera was a “real pro” who “always kept everyone laughing on the set”.
They added: “Our hearts go out to her family, especially her mom, Yolanda, who was a big part of the Glee family and her son Josey (Hollis).”
The creators are now establishing a college fund for Josey, who was found alone in the rented boat when his mother disappeared.
The Ventura County Sheriff’s Office said her last act may have been to help the four-year-old back onto their rented vessel before she became exhausted and drowned.
Glee cast members joined the show’s creators in telling of their grief and sharing memories of the star.
Gwyneth Paltrow, who is married to Falchuk, had a recurring role on the show and said she is in “utter shock and disbelief”.
She shared a clip from Glee of her performing alongside Rivera and described it as a “special moment”.
Dianna Agron starred in Glee as Quinn Fabray, a close friend and fellow cheerleader of Nivera’s Santana.
Alongside a poignant picture of her and Nivera touching noses, she wrote: “I cannot make sense of this tremendous loss. I will hold onto her and these memories for the rest of time, alongside our Glee family. Please hold space for her, her family, her beautiful boy.”
Darren Criss played Blaine Anderson on the show and paid tribute to a “wild, hilarious, beautiful angel”.
Demi Lovato, who played Rivera’s on-screen girlfriend, said she would “forever cherish” starring alongside her.
And Chris Colfer shared a lengthy tribute on Instagram, celebrating his more than 10-year friendship with Rivera.