The world number-seven-year-old fell 7-5-6-1.
World No. 1 Iga Swiatek is also eliminated following her 6-4, 6-2 loss against Russia’s Ekaterina Alexandrova, the 14th seed.
World No. 3 American Coco Gauff was taken aback by 23rd-seeded Caroline Garcia of France, who won 6-3, 1-6, 6-2 to make her first-ever final eight appearance in Miami.
The 34-year-old Azarenka, the two-time Grand Slam champion, will face Kazakhstan’s Yulia Putintseva in the quarterfinals.
Murray is ‘out for a lengthy period’ due to an ankle injury.
Garcia will face American Danielle Collins in the upcoming round after defeating four-time Grand Slam champion Naomi Osaka in the previous round.
Collins advanced to the round of eight with a 6-3, 6-2 victory over Sorana Cirstea of Romania.
In other action, Elena Rybakina, the fourth-ranked player in the world, defeated American Madison Keys 6-3, 7-5, and advanced to face eighth-seeded Maria Sakkari of Greece.
Following the withdrawal of her Russian opponent Anna Kalinskaya, Sakkari advanced to the quarterfinals with a resounding win.
