Usmani, a 1978-batch IAS officer, had taken voluntary retirement from service before taking over as the CIC.
As per rules laid down for appointment of CIC, no one serving any post in the government can take the charge.
58-year-old Usmani, who was due to retire in January 2016, had served as joint secretary of then Prime Minister Manmohan Singh between 2004 and 2007 and had worked in the capacity of senior advisor in World Bank and Indian Embassy in Nepal.
He earlier served as secretary to then UP Chief Minister Mulayam Singh Yadav in 2004 and was made Chief Secretary in 2012 after Akhilesh Yadav took charge as Chief Minister.
However, after two-and-a-half years, Usmani was removed and after being put on wait list for some time, he was appointed as Chairman of Board of Revenue, where he was serving before taking VRS.
He had applied for the post of CIC, which fell vacant in July last year.