Some 1,224 Joneses packed into the Wales Millennium Centre in Cardiff, smashing the previous record gathering of 583, set by the Norbergs of Sweden.
Guinness World Record officials had the task of keeping up with the Joneses and validated the attempt.
People with the Welsh surname from as far as Australia and the United States descended on event to take part.
All had to prove their identity, with maiden names and hyphenated surnames being ruled out.
Grace Jones, the flamboyant Jamaican-born 1980s pop star and former Bond girl, was among the famous Joneses entertaining their namesakes in the theatre.
Jones is the second most common surname in Britain, after Smith, with 431,558 Joneses in the country. Blaenau Ffestiniog, in northwest Wales, is the town with the highest proportion of Joneses in Britain.
Jones is the most common Welsh surname and means son of John.