The controversial far-right politician said he would not let his personal issues affect his party or his political career.
He also described the bankruptcy decision, at Welshpool and Newtown County Court earlier this week as a "good day".
The move had freed him from his money worries, he said, adding he is now writing a book on dealing with debt.
Mr Griffin, the leader of the BNP since 1999, was first elected as an MEP in 2009. A decade ago a bankruptcy order would have prevented him from standing for re-election. The rules, which also affect who can stand as a MP, were changed in 2004.
Mr Griffin said his bankruptcy would not affect his party or his career. "Being bankrupt does not prevent me being or standing as an MEP," he said.
"Party funds are not affected in any way. Our campaign in May will be our most professional yet and I will be lead candidate in the north-west."
Cambridge-educated Mr Griffin, a former member of the National Front, has long been a controversial figure in British politics. In the late 1990s he was found guilty of distributing material likely to incite racial hatred and was given a two-year suspended prison sentence.
By 2008 the party he led had won a London Assembly seat and two European Parliament seats followed the following year.
That year, however, also saw a controversial appearance on BBC Question Time, which he used to attack Muslim and gay people.
Mr Griffin later complained about the reception he received, saying it had been unfair to film the programme in London, a city known for its high number of ethnic minorities. Not long afterwards he was pelted with eggs as he arrived for an appearance at a radio station in Hamilton.
The following year he was barred from attending a garden party at Buckingham Palace amid accusations he "overtly used [his invitation] for party political purposes".
The BNP said Mr Griffin had been declared bankrupt after a petition by his former solicitors, Gilbert Davies, to pay over nearly £120,000 in outstanding debts.
Mr Griffin had earlier applied to pay 42p in the £1 to all his creditors over the next five years. He will be automatically discharged from bankruptcy in one year.
Mr Griffin said he was writing about his own experience of suffering from money problems, in a bid to help others.
"I am now much better able to advise and help the huge numbers of decent ordinary folk in my constituency who have financial difficulties of their own. I will be producing an advice booklet on dealing with debt very shortly and can speak from personal experience."
Bankruptcy in itself does not bar someone from being a member of the European Parliament or standing for election, according to the Electoral Commission, the elections watchdog.
Earlier this week, Mr Griffin faced protests after he used the word "Fenians" in a Christmas message. Addressing 27,000 followers on Twitter, he said: "Merry Christmas to all - even the foul-mouthed Glaswegian Fenians who must rate as my most vile followers."
Elections to the European Parliament will be held in May. Ukip is expected to top the poll across the UK.