Welson Sim Wee Sheng (born 29 March 1997) is a Malaysian professional swimmer.

He was the first Malaysian male swimmer to qualify for the men's 400 metre freestyle event at the 2016 Summer Olympics.

[2][5] He started joining swimming classes at the age of 10 to overcome childhood asthma, and competed in Sarawak's President Cup a year later.

[4][6] By the time he turned 12, he was in the Sarawak state swimming team.

[9] This biographical article related to a Malaysian swimmer is a stub.