Eric Brown opened the account for ONGC in the 19th minute which was assisted by Keniston C.
Lajong pressed hard for the equaliser but failed to find the back of the net and ONGC were leading 1-0 during half time.
After the break ONGC doubled the lead when Katsumi Yusa scored in the 49th minute.
SLFC made a couple of changes in the second half and brought in Boithang Haokip for Jibon Singh, Jacob came in for Renedy Singh and Bipin Singh for Friday Gbeneme in the 48th, 66th and 81st minute respectively.
Santosh Kashyap, the new manager of ONGC also made changes when he brought in David Lalrinuamana for Mollick, Puia for Kenniston and Jatin came in for Eric Brown in the 54th, 77th and 87th minute respectively.
The hosts then added another goal to make it 3-0, when Katsumi Yusa scored his second in the 80th minute and ONGC grabbed all the three points against North East side Shillong Lajong FC.
Shillong Lajong FC will host Pune FC on the 29th of December at the JN Stadium Shillong at 2PM.
While ONGC will take on USFC on the 29th of December in the 13th round of the I-League 2012-13 season.