Ryanair earned one star out of five for luggage allowance, boarding, legroom and food and drink.
The passenger survey, conducted by consumer watchdog 'Which?', surveyed 12,750 short-haul passengers on their experiences in the past year.
Guernsey's Aurigny Air Services came top of the poll, followed by Swiss International. Thomas Cook ranked just above Ryanair.
In the long-haul category, Air New Zealand and Singapore Airlines shared the top spot. Iberia was named as the worse airline for long-haul.
Ryanair has implemented a number of measures recently to improve its public image and services.