Bob Saget's wife Kelly Rizzo honored him on what would’ve been his 70th birthday ... sharing an emotional tribute alongside a sweet throwback clip of him smiling blowing out birthday candles.

In the emotional IG post from Sunday, Kelly reflected on how Bob would still be "going full steam ahead" if he were alive today -- saying retirement was never in his vocabulary and he’d still be making people laugh nonstop.

The post was a lengthy one ... admitting she often wonders what Bob would be doing today ... adding that while she feels lucky to have shared six years with him, she wishes the world got to see more of him.

Bob ended the post saying she was honored to continuing sharing all the Bob love, and asked others to join her in wishing him happy heavenly 70th birthday.

John Stamos -- Saget's former "Full House" co-star -- also took to his social media to honor his late pal ... saying "We used to throw each other the best birthday parties. Your 70th today would've been epic! I miss you and love you."

As TMZ reported ... Bob died in 2022 after suffering a fatal brain bleed following a head injury at the Ritz-Carlton in Orlando after a comedy show.

Authorities later said he likely didn’t realize how serious the injury was before going to sleep.