Sanchez was surrounded by a number of Seagulls defenders in the box but found Iwobi in space with a cute back heel.
The Nigerian kept his composure to fire past Matthew Ryan and double Arsenal’s lead following Nacho Monreal’s opener.
“It was a great team play,” Iwobi said. “I didn't think Alexis would find me but it shows the skill he has.
“He is capable of doing anything.
“To have eyes in the back of his head and back-heel to me was amazing.”
Arsenal were rarely troubled by Brighton and could have scored more to build up their goal difference.
The result lifts the Gunners to fifth in the table, level on points with Premier League champions Chelsea.
“I wouldn't say it was comfortable but we made it as easy as we could,” Iwobi added.
“It is always good to win the game and come away with a clean sheet.”
