The Lost River star and members of her family gathered at the Church of the Recessional in Glendale, California this week to celebrate the father-of-two's life.
Their younger brother, Carlo Mendez, had announced the sad news on Instagram.
He posted: "With absolute pain and sadness in my heart this is the hardest thing I've ever had to go through in my life and as I'm writing this I'm still in disbelief.
"My brother has passed away peacefully this morning.
"I want to thank you all from the bottom of my heart for those who have prayed and have kept my brother in your thoughts and who wished him to get better.
"He fought with all his might and power and gave cancer one hell of a fight. He leaves behind behind a 13 year old and a 5 year old. I love you my brother may god bless you and I'll see you once again"
And Carlo later shared details of the memorial service as he praised his "funny, charming, genius, comedian" sibling and thanked people for their messages of condolences.
He wrote: "To remember who my brother was and the impact he left on us. The amazing person he was, the funny charming genius comedian creative hot tempered crazy calm person that he was.
"I still can't believe this has happened. I'm crying as I write this and I have no idea how to cope with him being gone but I want to thank you all who have reached out to me and believe me when I say your messages make me feel a little bit better.
"My life will never be the same without him. Thank you all."
Eva - who is believed to be pregnant with her and Ryan Gosling's second child, a sibling for 19-month-old Esmeralda - hasn't commented on her sad loss, but three weeks ago she shared a black and white picture of herself and her brother at the Hollywood Stands Up to Cancer event in January 2015, captioning the image with just heart emoji.