The founder of the international Zamin mining group had acquired the large property overlooking the city's famous Regent's Park in October 2013 for 37.5 million pounds.
According to 'Evening Standard', Agarwal was hit by a big fall in his personal wealth last year following a collapse in the price of ore and a costly legal battle over a Brazilian mine.
But he has said the decision to sell the luxury home was more personal.
"I had to choose whether to live in Mill Hill (north London) or whether to live in Cornwall Terrace (Regent's Park). We thought we would move to town and see how it is but we didn't like it so we decided to come back here (Mill Hill)," he said in a statement.
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The former office building was originally two town houses knocked together during a refurbishment to create a single 11,233 sq ft residence, the newspaper reports.
The owners can enjoy a spa and gym in the basement, a first-floor grand reception room nearly 40ft-long with views over the park's boating lake and six bathrooms or shower rooms.
Agarwal, known for his flashy lifestyle in the UK,had become embroiled in a 145 million pound court battle with Kazakh mining giant ENRC over a Brazilian iron ore mine, which is now believed to have been settled.
The gardening and film buff had in 2014 spent an estimated 7 million pounds on the three-day Italian wedding of his daughter Ritika at the elite Borgo Egnazia resort in Puglia.
Three years earlier he threw a similarly spectacular wedding for his second daughter, Vinita, at Venice's San Clemente Palace, with singer Shakira as the star turn.
He now lives at the family's nine-bedroom residence in north London.