The former Wimbledon finalist endured an injury-hit season and has not played since retiring during the second round of the Montreal Masters this month.
Raonic, 28, will be replaced by Kamil Majchrzak of Poland, who lost in the final round of qualifying.
World number 22 Raonic also missed the French Open each of the past two years because of injury. He reached the last 16 on four occasions at Flushing Meadows.