The Westlife singer is said to have run up debts of up to £18 million, according to The Sun.
Filan's property firm Shafin Developments Ltd began running into troubles earlier this year owing around £4 million in April.
He had begun a repayment plan for the debts, and had "exhausted all other options" before declaring himself bankrupt.
"I have worked long and hard to reduce my debts, and I am devastated that it came to this," he said after the ruling at Kingston County Court, Surrey.
Filan's company was planning to build a development, community centre, office units, private clinic, gym, creche and 68 homes in Sligo, Ireland, but none surfaced.
Shane Filan has reportedly signed a solo record deal with Universal, and will release his debut album after Westlife complete their farewell shows.