Imahara co-hosted more than 200 episodes of the incredibly popular science programme between 2005 and 2014.
The electrical engineer and roboticist also starred in the Netflix series White Rabbit Project.
He is survived by his long-term partner, costume designer Jennifer Newman, who posted a heartbreaking tribute to Imahara on social media along with a series of photos of the happy couple.
"I haven't found the words. I don't know if I'll be able to. I lost a part of my heart and soul today," Newman shared on Twitter.
"He was so generous and kind, so endlessly sweet and so loved by his incredible friends. I feel so lucky to have known him, to have loved & been loved by him.
"I love you, honey."
Fellow Mythbusters hosts Kari Byron and Tory Belleci have been rocked by their friend's passing, with Byron sharing a poignant photo of the trio on Twitter today with the caption: "Somedays I wish I had a time machine".
Another former co-host and colleague Adam Savage also shared his grief on social media.
"I'm at a loss. No words. I've been part of two big families with Grant Imahara over the last 22 years. Grant was a truly brilliant engineer, artist and performer, but also just such a generous, easygoing, and gentle PERSON. Working with Grant was so much fun. I'll miss my friend," he posted.
It sparked an outpouring of sympathy and grief from fans.
Imahara studied electrical engineering at the University of Southern California and joined Lucasfilm after graduation, later working for the studio's visual effects branch, Industrial Light and Magic.
Before landing his role in front of the camera, he worked behind the scenes on a string of hit films including The Matrix, Star Wars and Jurassic Park flicks.
Week of tragedy
Tragically, Imahara is just the latest high-profile figure to have died suddenly in recent days.
Last week, 33-year-old Glee star Naya Rivera disappeared while boating with her four-year-old son on Lake Piru, with her body found five days later after a frantic search.
On Sunday, Lisa Marie Presley's only son and Elvis Presley's grandson, Benjamin Keough, died inside the family's mansion in California in a suspected suicide at the age of just 27.
And yesterday, former South African leader Nelson Mandela's youngest daughter Zindzi Mandela also died suddenly at age 59.
