A listing at the Insolvency Service showed Mr Griffin was declared bankrupt at Welshpool and Newtown County Court yesterday.
Mr Griffin tweeted: "Being bankrupt does not prevent me being or standing as an MEP. It does free me from financial worries. A good day!
"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.
"I am now turning the experience to the benefit of hard-up constituents by producing a booklet on dealing with debt. No surrender."
Mr Griffin will be automatically discharged from bankruptcy in one year, on January 2, 2015, in accordance with the Insolvency Act.
Mr Griffin was elected for the North West region of England in 2009.
Advice published by the Electoral Commission said bankruptcy in itself does not bar someone from being a member of the European Parliament or standing for election.
Restrictions are only triggered if an individual is made subject to a bankruptcy restrictions order or debt relief restrictions order.
The Insolvency Service said such orders had not been made in Mr Griffin's case.
Before April 1, 2004 being bankrupt itself would have disqualified a person from standing as an MEP or MP.
The restriction was amended as part of the Insolvency Act 1986 so only the addition of a Bankruptcy Restriction Order on top of being bankrupt means a person being disqualified.