Ryanair said it carried over one million US citizens across Europe during the summer season, up 50% on the previous year.
The airline said that record numbers of US customers logged on to its dedicated US website, which allows bookings to be paid in dollars.
California residents flew most with Ryanair, followed by citizens of New York, Florida, Illinois and Texas.
The airline noted that the most popular routes booked were Dublin-Edinburgh, Athens-Santorini, Barcelona-Rome, Frankfurt Hahn-London Stansted and Dublin-Amsterdam.
