Sotoudeh, a lawyer and human rights activist, is serving a six-year jail sentence after being arrested in September 2010 and convicted of spreading propaganda and conspiring to harm state security.
She began a hunger strike on October 17, according to the New York-based International Campaign for Human Rights in Iran (ICHRI), in protest against a ban on her 13-year-old daughter leaving the country and limits on visits by her family.
"After 49 days, Nasrin Sotoudeh ended her hunger strike ... after judiciary restrictions on her daughter Mehraveh Khandan were lifted," the opposition Kaleme website reported.
Sotoudeh's husband Reza Khandan told Reuters last week he was seriously concerned about his wife's health. According to ICHRI, Sotoudeh has suffered severe weight loss and has been taken to the prison infirmary several times.
The United Nations' top human rights official Navi Pillay urged Iran earlier on Tuesday to free Sotoudeh and to lift a travel ban on her family.
A parliamentary committee planned to visit Tehran's notorious Evin prison where Sotoudeh is being held due to concerns over her deteriorating condition, Iranian media reported on Sunday.
Sotoudeh and Iranian filmmaker Jafar Panahi were awarded the European Union's Sakharov prize for human rights and freedom of thought last month. Panahi has been held under house arrest since December 2010.
Sotoudeh has defended journalists and rights activists, including Iranian Nobel laureate Shirin Ebadi and Dutch national Zahra Bahrami, who was hanged in January 2011 on drug trafficking charges.
The United States demanded on Friday that Iran free Sotoudeh, and sharply criticised Iranian authorities for their treatment of her.
(Editing by Jon Hemming)