At the 2016 Summer Olympics, he competed in the men's 200 m individual medley event. He finished 9th in the heats with a time of 1:59.33. He qualified for the semifinals where he placed 11th with a time of 1:59.54 and did not qualify for the final.[2] He was a member of the men's 4 x 100 medley relay team which finished 15th in the heats and did not advance to the final.[3]
He also swam for North Carolina State University where he won the NCAA Championship Twice in the 200 Yard Butterfly, he was member of a two times NCAA Champion 800 freestyle relay breaking the NCAA record, ACC record and school record. Andreas was the 2019 scholar athlete.
Andreas Vazaios is a member of the London Roar team, competing in Season 2 of the International Swimming League (ISL). The ISL is an annual professional swimming league featuring a team-based competition format with fast-paced race sessions.