"One of my priorities was that I wanted to have continuity for my future as a rider, and so I thank UAE Team Emirates for giving me the opportunity to allow me to work with them towards my goals," Costa said.
"It is a great boost to know that we have the confidence of the whole team, and I am really happy to still be part of the great cycling project that is UAE Team Emirates.”
UAE Team Emirates also signed 21-year-old Italian Alessandro Covi from Team Colpack, and under-23 time trial world champion Mikkel Bjerg from Hagens Berman Axeon.
How Bjerg secured terrific hat-trick in U23 world time trial
"I can't wait to face this new cycling challenge," said Covi. "I'm happy to do it at a big team like UAE Team Emirates and alongside some great champions.
"The team has put a lot of faith in young riders, and I think I will be in the best place in order to reach the goal of giving my best.”