Querrey overcame Lukasz Kubot 4-6 6-3 6-3 to secure his place in the next round.
"I started out a little slow," he told the tournament's official website.
"He broke me the first game, but then he served really well rest of the first set.
"But after that, I felt pretty good second and third sets. I served big and hit my forehand well. I was pretty happy."
There were also wins for France's Jo-Wilfried Tsonga, Italy's Andreas Seppi, Belgium's David Goffin and eighth seed Richard Gasquet.
Sunday's action is set to include World No.1 Novak Djokovic, who is looking to win a fourth Miami Masters title
Djokovic, who destroyed Lukas Rosol 6-1 6-0 Friday, will take on India's Somdev Devvarman, currently ranked 254th in the world.
But one man who won't be on court is fifth seed Juan Martin del Potro after he was sent crashing out in the second round by Tobias Kamke.
Del Potro reached the final at Indian Wells last week, but was unable to see off 89th ranked Kamke.
"I was excited to play here, but [it was] just a bad day and he [played] really well," the Argentine told the tournament's official website.