 Vieru won medals at a number of IJF Grand Prix and Grand Slam events in 2019, including Moldova's first Judo Grand Prix gold medal at the Antalya Grand Prix, another gold at the Baku Grand Slam, and defeated 2016 European champion Vazha Margvelashvili to win gold at the Grand Slam Paris.He also defeated Ranto Katsura of Japan to win a gold medal at the 2019 Summer Universiade in Naples, where he was the flag bearer for the Moldovan delegation in the opening ceremony, and won a bronze medal at the 2019 World Judo Championships.As of February 2020, he was ranked third in the world in the men's half-lightweight category.