Oliech showed flashes of his brilliance when he found the back on the net in first-half stoppage time against Posta Rangers at Safaricom Stadium Kasarani.
Oliech was making his full debut for the 17-time league champions, having previously come in as a substitute.
In K'Ogalo's game against Mathare on Sunday last week, Oliech was brought in from the bench. Gor drew 1-1 with the slum boys.
On January 2, Gor Mahia signed the player who returned to domestic football 15 years since featuring for Mathare United as a teenager.
Oliech will earn Sh350,000 a month, with his signing fee reported to be worth more than Sh3 million, which will be paid in two installments, according to his representatives.
The all-time Harambee Stars goal-scorer with 34 goals penned a two-year deal after holding talks with the club.
Oliech who had been out of active football for more than two years last featured for Dubai Cultural Sports Club in the Arabic League. The 33-year-old is also a former Auxere and Nantes striker in the French League 1.
Nicknamed Dennis the Menace, Oliech is expected to fill the boots of Rwandese striker Meddie Kagere who left Gor for Tanzanian giants Simba.
-The Star