On 25 January 2012 it was announced that Kumar Singh has signed back into the I-League with Shillong Lajong.
[2] 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.
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.
He has been signed on by the NEROCA FC from Manipur and scheduled to play in the 2016-17 Durand Cup in Delhi.
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.