DNA tests have revealed that Larry Birkhead, a former boyfriend of the late Playboy model, Anna Nicole Smith, fathered her baby daughter, Dannielynn.
Ms Smith died of an accidental overdose of sleeping pills
Ms Smith's partner and lawyer, Howard Stern, is one of two other men who have now lost a court case in which they tried to prove they fathered the child.
Dannielynn could inherit millions if her mother's estate wins a legal battle over a previous husband's legacy.
Mr Birkhead told reporters he planned to buy new toys for his daughter.
Standing on the steps of a courtroom in Nassau, Bahamas, the Los Angeles-based photographer said: "I hate to be the one to tell you this but - I told you."
"Nothing's really determined except parentage and I'm the father," he said. "I'm going to the toy store."
Ms Smith died aged 39 of an accidental overdose of sleeping pills in a Florida hotel on 8 February.
She lived in the Bahamas for the last months of her life and was buried there.
Her daughter's Bahamanian birth certificate listed Ms Smith's partner, Howard Stern, as the father.
On Tuesday, Mr Stern appeared alongside Mr Birkhead to say he was very disappointed by the DNA test but he was going to do his best to ensure Mr Birkhead got full custody of the child.
The two hugged each other outside the courthouse after the test results were revealed.
Along with Mr Stern and Mr Birkhead, Hollywood actress Zsa Zsa Gabor's husband Prince Frederick von Anhalt also claimed he had fathered the child.
Dr Michael Baird, the American DNA expert who conducted the test, said he was 99.9% certain that Mr Birkhead was the father.
The ruling does not decide who gets custody of Dannielynn however. That is to be determined at another hearing set for Friday.
Mr Birkhead said he was going to buy toys for his daughter
Ms Smith's estranged mother, Virgie Arthur, has indicated she may seek joint custody of Dannielynn.
Ms Arthur had sought to have her daughter buried in her native Texas instead of the Bahamas, where she was buried next to her son, Daniel.
Daniel died in September 2006 just a few days after Dannielynn was born.
The baby could inherit millions of dollars if Ms Smith's estate wins an ongoing legal battle with the heirs of her former husband, Texas oil billionaire J Howard Marshall.
They married in 1994 when he was 89 and she, at 26, a recent Playboy Playmate of the Year.
He died 14 months later.