Prior to that, the climber rode for Bahrain-Merida and Lampre, having turned pro with MTN-Qhubeka in 2013.
Grmay is the reigning Ethiopian time trial champion, taking his fifth national title in the discipline in June, while he is also a three-time national road race champion, having won the title in 2013, 2104 and 2015.
His only other pro wins have come at the African Continental Championships individual time trial in 2014, and a stage at the Tour de Taiwan in 2013.
However, Grmay's goal is to one day win a stage at the Tour de France.
"When I said back in 2010 and 2011 that my dream was to ride the Tour de France one day, people laughed at me and said it was impossible. But after six years I made it," Grmay said in a Mitchelton-Scott press release.
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"Now I believe it's possible that I can win a stage at the Tour de France. That's my dream, and every morning I wake up and that is my goal, and my life, and one day I will do it, for sure," he said. "It will be hard, but it was hard to be the first Ethiopian to make the WorldTour and race the Tour de France, so why not?"
Grmay said that he's very excited to be joining Mitchelton-Scott.
"When we got the get the call from the team, it was an easy decision because I have been following the team for many years. What the team do in terms of having fun off the bike, but keeping it serious business on the bike, fighting for the win... I want to be part of that.
"I always try to push myself, and smile as much as I can, so it will be perfect with the team," he continued. "I will come in with the role of supporting the GC guys on the climbs, and that will be my main job. I will of course be wherever the team want me to be, especially on the hard mountain days, and I'll work hard for that, and I'm ready."
Head sports director Matt White confirmed that Grmay's main role will be to help the team's leaders at the Grand Tours and at hillier races.
"Tsgabu has an interesting story," White said. "He hasn't had the normal development through cycling that most of our guys have had, but he is quite an experienced campaigner. He started his career with what was MTN-Qhubeka [now Dimension Data], and he has had a couple of different teams these last years.
"He is a little fighter, and he's a solid little climber. He's only 27, but he's a very versatile guy. He time trials well, he climbs well, and he is another guy that we're going to use to back up our leaders in a lot of the 'climber races' throughout the season."
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