Rybakina will meet the winner of Thursday's other semi between American Danielle Collins and Russian Ekaterina Alexandrova.
The 24-year-old returns to the Miami final for the second straight year after losing to Czech Petra Kvitova in 2023. Her form - and the absence of any of the top three in the world - suggests she will be the strong favorite whoever makes it to face her in Saturday's title showdown.
So far this year, the Kazakhstan player has won titles in Brisbane, Abu Dhabi and her first WTA 1000 final of the year in Doha.
Her serve looked too much for Azarenka in the first set but then faded badly in the second before breaking to go 3-2 up in the third. But the 34-year-old Azarenka, a three-time winner at Miami, showed all her dogged spirit as she broke back to make it 5-5 and keep alive her hopes of an unlikely run to the final.
However, in the tie-break, Rybakina found her serve in spectacular fashion, leaving Azarenka helpless with a fearsome ace to go 3-0 up.
The outcome never looked in doubt from that point on but 2022 Wimbledon champion Rybakina, who withdrew from her Indian Wells title defense this month because of illness, said she had been in trouble physically in the second set.
"There was a pause where I stayed on the court and I think I should have maybe left (for) a bit because it was really humid and tough conditions, the energy just went down and Vika came back very aggressively.
"After three games when I lost so easily it was very difficult to regroup so I knew there would be a third set and I was just trying to prepare for it," she added.
Rybakina said she was able to get in the zone for the tie-break. "I switched off the mind a bit for the tie-break and I just went for it," she said.
