The former world number one beat Collins 6-2 6-1 to progress after just an hour of playing.
Prior to this tournament, Osaka had a difficult outing at Indian Wells after a heckler left her in tears.
At both Indian Wells and the Australian Open back in January, the four-time Grand Slam champion has suffered early exits. But in Miami, Osaka looks to have hit the ground running once again, yet to drop a single set so far.
The 24-year-old will face Switzerland’s Belinda Bencic in the last four.
Bencic has also not dropped a set this tournament, and the odds are in her favour. She has beaten Osaka in four of five of their previous meetings, most recently in 2019.
The semi-final will take place March 31.