In April 2019, he won a silver medal in the men's singles competition during the World Championships in Budapest, Hungary, after losing the final to Ma Long from China.

[10] In 2020, Falck upset Xu Xin at the WTT Macau event in ITTF's restart campaign following the coronavirus pandemic.

In the team event, Sweden defeated USA in the first round 3–1, but Falck was upset Kanak Jha.

[14] Sweden lost to Japan in the quarter-finals after Koki Niwa upset Falck in the fourth round.

[17] In September Mattias Falck was playing in the Swedish National team that won the 2023 STUPA European Table Tennis Championships in Malmö.