Antony Costa has declared himself bankrupt - leaving Lee Ryan the only member of Blue not to have gone broke.
Bandmates Duncan James and Simon Webbe both took on the legal status last year when they were unable to pay their debts and the band's firm Blueworld Ltd has also gone bust.
Now Antony, 33, whose fiancee Rosanna Jasmin gave birth to baby girl Savannah in June, has told The Sun he is also bankrupt.
He said: "I am really proud to be a father and the arrival of my new daughter has made me take a good look at my finances.
"I want to be sure I can provide the best possible future for my family.
"Our former management made a lot of decisions that we as a band have had to be financially responsible for. Whether right or wrong, their personal pursuit in the last two years has led me to instigate proceedings to wipe the financial slate clean and start again."
Fellow Blue star Simon has just signed up to take part in the BBC's Strictly Come Dancing, propelling the boyband who formed in 2000, back into the spotlight.
Bandmate Lee, 31, has had a string of legal troubles over recent years, most recently appearing in court for drink-driving and criminal damage earlier this year. He also took part in the last series of Celebrity Big Brother.