Mohammad Hossein Karrubi also posted a picture of the visit, the first photograph of his father that has been seen in months. He wrote that his father, who has been under arrest for more than a year, was brought to the family house in Jamaran.
He did not provide any further details.
The opposition website Sahamnews reports that Karrubi is now being held not at home but in "a building" under the watchful gaze of security agents.
Fellow opposition leader Mir Hossein Musavi and his wife, Zahra Rahnavard, have also reportedly been under house arrest for some 450 days.
The opposition figures were put under house arrest after their February 2010 call for a rally in support of the uprisings in Tunisia and Egypt attracted tens of thousands of protesters.