Mahindra United Singh started his footballing career at
Mahindra United in the
I-League and scored eight goals in eleven games while with Mahindra till Mahindra disbanded.
East Bengal After
Mahindra United disbanded Singh joined another
I-League club. This time it was
Kingfisher East Bengal F.C. During his first season with East Bengal in
2010-11 Singh played in five games and scored one goal.
United Sikkim In July 2011 it was reported that
United Sikkim F.C. of the
I-League 2nd Division have signed Singh on a one-year contract after Singh talked with
Baichung Bhutia.
Shillong Lajong On 25 January 2012 it was announced that Kumar Singh has signed back into the
I-League with
Shillong Lajong.
Atlético de Kolkata Signalling his steady decline in match-readiness and age, in July 2015, Singh was drafted to play for
Atlético de Kolkata in the
2015 Indian Super League, being ineligible for any of the auctions.
Mumbai FC He has been signed on by the thrifty
Mumbai FC for the
I-League2015-16 season where he is on loan from Atletico de Kolkata. He is seen as the fallback forward in the club featuring a few prominent Japanese players. While, his and the club's performance for most of the season has been lacklustre, he has managed to score 4 goals during appearances which did not feature the primary scorer for a team which has been plagued with injuries.
NEROCA FC He has been signed on by the NEROCA FC from Manipur and scheduled to play in the 2016-17 Durand Cup in Delhi. This is club participates 2-steps below the divisions of the leagues that he has been participating in the last couple of years. While, the club made it to a historic final on its debut at the Durand Cup 2016 riding on the effort of the young manipuri team, the team lost the trophy in penalties to Army Green when Sushil hit a ground sitter to the opposite goalkeeper. ==International career==