Born in Hanoi, Thanh Long was a youth product of the army's club Thể Công.
Left without a club, Thanh Long abandoned his football career on the advice of his parents and worked at the Ministry of Public Security.
[2] In 2018, through some connections, Thanh Long went for a trial at V.League 1 side Becamex Bình Dương and was signed by the team, making his return as a footballer.
[5] He featured in the 2023–24 Vietnamese Cup final, playing the full 90 minutes in a goalless draw against Hà Nội.
In the penalty shootout, he succeeded in his attempt as Thanh Hóa won 9–8 and were crowned champions.