The Men of Steel took a first half lead through Billu Telli in the 35 minute which went unanswered in half-time.
The youngsters from Jharkhand looked good value for their lead at the start of the second half but a revitalised Chawnpui FC proved to be too much to handle as they conceded an own goal from Subham Ghosh on the 54th minute.
Bouyed by their equaliser, Chawnpui FC pressed on and found their winner through Lalramliana midway into the second half.
Jamshedpur FC will come up against Kanan FC in their next match on Friday afternoon while Chawnpui FC will battle the same opponents on Monday evening.
MATCH STATS
Chawnpui fC 2-1 Jamshedpur FC
(C: Subham Ghosh 54′ own Goal, Lalramliana 76′; J: Billu Telli 35′)