The 19-year-old opened the scoring at Bramall Lane as Arsenal fought to a 2-1 victory over the Blades to make it three wins from a possible four so far this season.
A slick passing move set Bellerin free down the right of the Blades' box though, before he clipped a delicious cross over to Saka at the back post to head in.
Speaking after the game, Saka said: "After I celebrated I told Hector what a cross it was because it was perfect.
"The type of patterns we work on in training everyday just to build up and attack the wide areas to get the crosses in.
"I made sure I was there at the back post and luckily it came to me."