Delegates at Usdaw's Annual Delegate Meeting voted unanimously for the Government to regulate holiday companies and stop the practices of charging adult prices for 13-year-old children and significantly increasing prices during school holidays.
The vote follows comment from Prime Minister David Cameron,who accused some travel companies of "deliberately" putting up prices outside term time.
The Prime Minister said he shares the "frustration" of parents who face higher bills for breaks taken during school holidays, and that schools should vary their term dates so prices do not surge on a specific day.
During an interview in Birmingham, Mr Cameron said: "This is very frustrating and I have seen it myself when you are booking on Easyjet or Ryanair.
"Prices go up because of the demand and then you've got holiday companies who sometimes seem to deliberately put up prices at holiday time."
Speaking at the conference, Paddy Lillis, Usdaw general secretary, said that household budgets are being squeezed by below-inflation pay rises and cuts to in-work benefits, and that goods and services needed to be fairly priced.
He said: "Holiday companies have the well-earned reputation of being creative in maximising profits and imposing tough conditions on customers.
"Studies have shown that travel firms, airlines, hotels and other businesses inflate prices when schools are on holiday. Prices can soar by up to 200%.
"However, there is another way in which families who wish to take holidays are financially hit. The age limits used by some of the holiday companies, which consider a 13-year-old an adult and charge adult prices accordingly.
''This is unacceptable. Ending this profiteering would allow families to take holidays and spend some quality time together."