The Glee actress’s body was found in Lake Piru on July 13, four days after she went missing while on a boat trip with her four-year-old son Josey.
The 33-year-old’s death was ruled an accidental drowning. Police said Naya “mustered enough energy” to boost her son back onto the rental boat, saving his life, before he saw her disappear beneath the surface.
Big Sean, 32, has now broken his silence as celebrities and fans across the world mourn the star’s loss.
In a heartfelt post on Instagram, liked more than 300,000 times, he wrote: “Rest In Peace Naya, God Bless your Soul!
“Thank you for blessing us all with your talent and presence. you are a hero!
“Not just because of how you saved your son, also because of the barriers you knocked down for so many people to make them feel confident in themselves and to stand tall and be proud when they couldn’t achieve that on their own.
“I appreciate and cherish everything that ever happened between us for making me wiser and a better person. I’m still grieving and in shock, I can’t believe this is real.
“I’m praying for you and your family and I know your watching over them and protecting them. Rest In Peace Naya.”
The rapper, who was engaged to Naya in 2013, accompanied the post with two pictures of Naya, one showing her cradling her young son, whom she shares with ex Ryan Dorsey, 36.
Stars including Macklmore and Snoh Aalegra left heart emojis under the emotional post.
Big Sean and Naya began dating in 2013 after Sean’s split from Ashley Marie.
Naya told Access Hollywood at the time: “I had followed him, and he sent me a little message like, “I’m a fan”. We went to dinner and the rest is history.”
During their relationship, Sean featured on Rivera’s debut single, Sorry, released in September 2013.