Ismayilova had appealed against a court decision made on March 6, which allowed for her to be held in pre-trial detention until May 24.
The award winning investigative journalist for Radio Free Europe (RFE) was arrested on Dec. 5, 2014, when a court ordered her to be detained for two months pending a trial on the unusual charge of inciting a former colleague to attempt suicide.
Her detention has been extended twice since then, most recently at the March 6 hearing.
Prosecutors have also charged Ismayilova with running an illegal business, tax evasion, embezzlement and abuse of power.
Ismayilova denies the allegations and no date has yet been set for her trial.
According to one of Ismayilova's lawyers, Fakhraddin Mehdiyev, the court also dismissed the lawyer Yalchin Imanov from her defense.
Orkhan Babayev, an investigator for the prosecution, said that since Imanov was questioned as a witness during the raid of the RFE offices in Baku, he cannot represent her in court.
Imanov argues that the two are separate cases, and that there is no legal basis for the block.
Human rights organizations have called Ismayilova's charges politically motivated. She was author of a number of investigations into the financial activities Azerbaijani President Ilham Aliyev's family.
She revealed business connections between Aliyev's daughters and Azercell, the country's largest telecommunications provider. She also revealed the family's secret investments into gold and silver mining, Czech real estate, and the Eurovision Hall.
