"Omanyala was called to the Ministry of Sports this morning and was handed the visa to travel," his coach Duncan Ayiemba told AFP.
"He will have a few hours to rest before he competes in the 100m heats (Friday), and hopefully qualify for the semi-finals and the finals."
The 26-year-old Kenyan sprinter -- the third-quickest man in the world this season -- had given up hope of competing after failing to receive the travel visa necessary to reach the fixture in Eugene, Oregon.
Championship organisers Oregon22 and World Athletics on Wednesday said they were following up visa issues for some athletes, adding the Covid-19 pandemic had made international travel more challenging.
Omanyala's time of 9.85 seconds in May puts him behind only American duo Fred Kerley and Trayvon Bromell in times run this season.
In September last year, he set a new African record of 9.77sec, making him the ninth-fastest man ever.
He told AFP in a recent interview he had set his sights on at least reaching the final of the 100m in Oregon, targeting a time of 9.6sec.