The Uzbek billionaire has pledged not to sell his shareholding, despite majority shareholder Stan Kroenke triggering a mandatory buyout when he took his holding to 66.1% in April.
Usmanov's Red and White Holding company said in a statement: "Red & White today announces that it now holds a stake of over 29% in Arsenal Holdings plc." The Uzbek bought into Arsenal in August 2007 when he paid £75m for David Dein's 14.65% stake in the club.
The Premier League gave the go-ahead last month for Kroenke's takeover. The American businessman bought the stakes of Danny Fiszman (16.1%) and Lady Nina Bracewell-Smith (15.9%) for a fee of about £234m and has given the club's remaining shareholders 14 days notice on his offer to own 100%.
Usmanov is joined by the Arsenal Supporters Trust who are also claiming that they will not sell their shares to the American.