Al Hilal's superiority was never in doubt as they controlled proceedings from the start at the Zabeel Stadium in Dubai.
But the Saudis struggled to breach the Shahr Khodro defence, with goalkeeper Mehdi Rahmati producing a string of some good saves in their Group B clash.
Just when it appeared the deadlock would continue into the second half, Shahr Khodro, who are making their Champions League debut, caved in to the pressure.
Italian international Sebastian Giovinco cut in from the left and passed for Salem al-Dawsari, who in turn set up Carrillo neatly and the Peruvian made no mistake with his half-volley.
Carrillo turn provider in the 69th minute as he received al-Dawsari's pass inside the box and squared for Gomis and the Frenchman, who was the top-scorer in the tournament last year, scored from just three yards with a simple tap-in.
Shahr Khodro could have pulled one back but Al Hilal goalkeeper Abdullah al-Mayouf made a fine save three minutes from time to thwart a powerful shot from Milad Sarlak.
Earlier in another Group B match, Uzbekistan's Pakhtakor edged out Shabab Al Ahli Dubai 2-1 in Tashkent.
Jaloliddin Masharipov became the first player to score in the tournament this season as he put Pakhtakor ahead in the 18th minute with an excellent lob over goalkeeper Majed Naser after having made considerable ground with the ball.
Pedro Conde however put Shabab Al Ahli on level terms in the 67th minute after Youssef Jaber's bicycle kick was saved by Pakhtakor goalkeeper Eldorbek Suyunov, leaving the Spaniard with a simple shot from close.
The Emirati side however couldn't take advantage of the momentum as Serbian Dragan Ceran restored Pakhtakor's lead in the 70th minute with a low shot following a right wing cross by Dostonbek Khamdamov.
Shabab Al Ahli had a couple of chances later but Pakhtakor held on.
Also on Monday, Iran's Estheglal drew with Iraq's Al Shorta 1-1, while the match between UAE's Al Wahda and Saudi Arabia's Al Ahli also finished one a-piece.