Sumaya Rajab said security forces searched the family house before they arrested her husband. No reason for the arrest was given, the Arabic language al-Wasat newspaper reported her as saying, and there was no immediate comment from authorities.
Rajab, founder of the Bahrain Centre for Human Rights, played a leading role in Shia-led demonstrations in the 2011 demonstrations demanding reforms in the Gulf Arab kingdom.
Bahrain, where the US Navy's Fifth Fleet is based, quelled the 2011 protests but has since struggled to resolve political deadlock between the government and the opposition.
Rajab was jailed in May 2012 on charges of organising and participating in illegal protests and released two years later.
In January 2015, he was sentenced to six months in jail over remarks deemed insulting of the kingdom's security establishment. He appealed against the verdict but an appeals court confirmed the ruling in May 2015.
He served two months in jail before King Hamad bin Isa al-Khalifa ordered his release by special pardon due to his poor health.
