Land Registry documents show that two properties on the seventh and eighth floor of the luxury development have been bought by a single buyer, the total consideration amounting to £136.4m.
Confirmation of the sale had been expected for some time, with news that a purchaser had paid the huge sum emerging last year. It has been estimated that the buyer would also be spending £60m fitting out the property.
A spokesman for Akhmetov's company, System Capital Management, confirmed the oligarch had invested in the development, which has caused uproar among local residents because of its modern architecture.
Akhmetov, the son of a coal miner, runs SCM, a Ukrainian conglomerate involved in mining, retail, financial services and even football – it owns the club Shakhtar Donetsk.
Estimates of his fortune vary, although most agree he is worth billions of pounds. As the owner of Metinvest, a coal, ore-mining and steel business, his net worth is likely to have soared over the past year on the back of the commodities boom, with Forbes recently estimating his fortune at $16bn (£10bn).
Buyers of flats in One Hyde Park are treated as permanent guests of the Mandarin Oriental, the hotel adjacent to the development. As well as outlining the property bought in each case, each lease document also specifies which area of the development's wine cellar the buyer is entitled to. Akhmetov will be able to store his collection of fine wines in wine storage spaces 16 and 17.
The flat is reported as having an area of 25,000 square feet, meaning the Ukrainian billionaire has spent £5,456 a square foot.
That is less than the absolute peak figures the developers, Nick and Christian Candy, had hoped for – with the highest flats with the best views of Hyde Park expected to go for as much as £6,000 a square foot.
The brothers are unlikely to be too bothered, however. Total sales of about half the flats have reaped £963m, the Candys have indicated, enough to almost pay off the £1.1bn cost of the development.