The bay was named ninth best worldwide, moving up from tenth in last year's survey.
It was also in the top three best in Europe, behind beaches in Lampedusa, Italy, and Formentera in Spain,
Economy minister Edwina Hart said being named a top world beach could "change perceptions about Wales".
The beach was ranked ahead of places in the Seychelles, South Africa and destinations in Mexico and Australia.
According to the voters, the world's best beach is Baia do Sancho in Brazil's Fernando de Noronha, an island archipelago with UNESCO world heritage status.
However TripAdvisor said Rhossili's ranking proved that people in the UK did not have to go halfway round the world to find a good beach.
James Kay, a spokesman for the company, said: "These awards recognise the best beaches in the UK and worldwide, according to the travellers that have visited and given them the highest levels of praise.
"To have a Welsh beach named among not only the best in Europe, but the best in the world, just goes to show how lucky we are in the UK to have such stunning scenery right on our doorstep."
Last year, a travel writer from Australia expressed amazement that Rhossili could be listed ahead of many beaches in his home country.
Swansea councillor Nick Bradley called the news "fantastic", adding: "The national and international exposure that this award brought Rhossili Bay in 2013 was both appropriate for all those involved in its upkeep and significant in terms of the impact it has had on the tourism industry locally and nationally."
In the UK poll, Woolacombe beach in Devon and Porthminster beach in Cornwall came second and third.
Edwina Hart said: "It's fantastic news for Wales that Rhossili has kept its title as the UK's number one beach for the second year in a row, seeing Rhossili named among the best beaches in the world can change people's perceptions about Wales and also instils an enormous amount of pride locally in what we have to offer as a holiday destination.
"Having this news just before the Easter holidays is a welcome bonus and hope it inspires many more people to visit Wales this year."
Rhossili beach in Gower has been named one of the top 10 beaches in the world and the best beach in the UK in a survey by travel website TripAdvisor.