Cherie's solicitor Graham Atkins confirmed a claim had been made "in relation to the unlawful interception of her voicemails" against News International and private investigator Glenn Mulcaire, who was allegedly hired by the closed tabloid to hack into phones of celebrities and others for information to be used in sensational stories.
"I can confirm that we have issued a claim on behalf of Cherie Blair in relation to the unlawful interception of her voicemails. I will not be commenting any further at this time," a statement from Atkins said.
News International had settled 37 civil actions in January, and had paid out to another 21 victims of phone hacking earlier this month.
The company is also seeking settlement with singer Charlotte Church, whose legal action will proceed to a full trial at the high court on Monday unless it is settled beforehand.
Many more civil actions are likely to be mounted against News International.
Alastair Campbell, the former communications director during Tony Blair's tenure as prime minister, told the Leveson inquiry in November that he believed it was "possible" that some stories about the Blairs were obtained by phone hacking.