Upvote:1
A visa denial makes you no longer excempt from the visa requirement, period.
An ESTA (which anyone who is excempt would need) would be automatically denied.
So yes, you need to go to the embassy or consulate and apply like everyone else who needs a visa to enter the USA.
If you try to board a flight to the USA from anywhere without a valid ESTA or visa, you're almost certain to be prevented from even checking in, let alone boarding. Not only do the airlines strictly enforce this as if they don't they face quite serious consequences from US authorities, but also US immigration officials are present in several countries interviewing people who want to board in order to weed out people who would not be allowed entry despite having an ESTA before the flight even takes off.
Upvote:6
Several years ago what you're saying would have been possible - with a UK passport you could have boarded a flight to the US, and then likely be refused entry once you arrive in the US (or not, depending on the circumstances).
Avoiding this type of situation is one of the reasons that the US instigated the "Electronic System for Travel Authorization", or "ESTA". Under ESTA, anyone planning to arrive in the US by air and enter using the Visa Waiver Program will first need to obtain an "ESTA", or you will not be allowed board the flight.
Based on the limited information you've provided, it's likely an ESTA would be rejected - but you can certainly try applying.
And remember, lying on a visa (or ESTA) application will only make things worse, and could result in action up to and including a lifetime ban from entering the US.