Freivalds, an expert on European affaires, will succeed the late Anna Lindh, who died last month from a knife attack.
Although she has no formal experience in diplomacy, Persson told reporters that she “dealt with EU questions more than anybody else” by taking part in legal cooperation talks between European Union members as justice minister.
She is a lawyer by training, and was justice minister for a total of nine years before leaving Persson’s previous government in 2000.
Freivalds will have her work cut out for her as she attempts to steer Sweden through the complex negotiations in the Intergovernmental Conference which is to give the EU a new constitution.
Controversial real-estate scheme
She left Persson's previous government in 2000 amid controversy over her decision to buy the apartment she was occupying in a privatisation operation, going against the line of the government which wanted to keep housing in the public sector.
Before accepting the new job, Freivalds said she had taken a few days to make up her mind about "this important mandate" for which she would have to put much of the rest of her life on hold.
Anna Lindh died in hospital on 11 September after an attacker stabbed her multiple times as she was leaving a department store the previous day. The popular politician’s murder led to a public outpouring of grief in Sweden and the international diplomatic community.
Prosecutors have until the end of next week to bring formal charges against a suspect held in connection with the attack.