"He has completed the procedures and he has come out," interior ministry spokesman General Hani Abdel Latif told AFP.
Adly's lawyer, Mohamed el-Gendy, said the once-feared interior minister who ran Mubarak's security service with an iron grip was at home.
A Cairo court on March 19 acquitted Adly of corruption charges, in the last in a string of cases he faced.
He had been accused of illegally accumulating around 181 million Egyptian pounds ($25 million/23 million euros).
More From This Section
The verdict was the latest in a series of acquittals for Mubarak-era officials, including the veteran leader himself.
An appeals court last month overturned a suspended five-year sentence slapped on Adly and ex-premier Ahmed Nazif over other corruption charges.
Adly was also cleared of murder charges in a separate retrial with Mubarak in November, for which he had been sentenced to life in prison by a lower court.