Raised at FC Reipas school he debuted for the first team 1st February 2013 in the League Cup against TPS Turku. FC Lahti won the trophy that year although Tuominen did not participate in the final. But he filled this gap in League Cup-2016 when he played all 120 minutes against our last year's opponents SJK Sejnajoki (0-0). Penalty shootout was the star moment for Lahti players who won 4-3.
In 2013 and 2014 seasons Tuominen played most of the time at FC Lahti Reserves from Division 3. In the spring of 2015 he was loaned to MP from Mikkeli. He spent half a year there only to signal to FC Lahti coaches with his outstanding play and goals. He was called back to Lahti and quickly became a first-team player.
In 2016 he was already Lahti leader and top-scorer with 10 goals. 9 January 2017 he debuted for Finland in a friendly against Morocco appearing as a substitute after 73 minutes (1-0). And then he played 30 minutes in the next friendly vs Slovenia (0-2).
In March 2017 he moved to FC BATE on permanent tranfser.