Acting on intelligence, officers from the Border Agency's Thames Valley immigration crime team stopped the wedding at the Oxford Register Office at around midday on Tuesday.
The would-be bride, a 19-year-old Polish national, and 'groom' Singh Dhanju, 30, were both arrested on suspicion of perjury.
Two witnesses were also arrested on suspicion of assisting illegal immigration.
All four were questioned by police and immigration officers. The teenage bride arrived wearing a flowing layered white dress with a satin veil covering her head, while Singh Dhanju wore his best suit, a smart bow tie and a red flower in his lapel.
Moments before the ceremony was due to start at the registrar's office, plainclothes police and immigration officers burst through the doors and arrested the two.
The registrar's suspicions were aroused when she met the couple to discuss the wedding ahead of the big day.
She called immigration officers and the trap was set by officers from Thames Valley Police and officials from the UK Border Agency.
Terry Gibbs, head of the UK Border Agency’s Oxfordshire local immigration team, said: "We are working closely with registrars to identify marriages that may not be genuine, and where we suspect that may be the case we will investigate.
We are committed to striking at the heart of illegal immigration and tackling those who break the rules."
An increasing number of EU citizens are marrying non-EU foreigners to help them settle in the country and enjoy the same rights as British nationals. In 2009, 529 such fake weddings were reported.