Use when someone achieves a huge success that's recognized and celebrated widely. After her app went viral, she certainly had the world at her feet.
Pro Tip 2/3
Not Literal
This phrase is figurative, meaning the person is esteemed highly, not physically standing over the globe. Being the lead in a hit Broadway show, he now had the world at his feet.
Pro Tip 3/3
Widespread Admiration
Implies popularity or love from people in different places or cultures, not just local fame. With her Olympic gold medal, she suddenly had the world at her feet.