The Spaniard, who has come under scrutiny since his move to Old Trafford from Atletico Madrid in 2011, has been linked with a possible exit following reports that United were looking elsewhere.
Stoke City shot-stopper Asmir Begovic has been heavily tipped to move to the North-West outfit in the summer, but Ferguson has confidence that De Gea will cement the number one spot.
"David de Gea has developed and matured as the season has gone on," The Guardian quotes Ferguson as saying. "We've seen a very progressive and developing young goalkeeper and next season he'll be even better."
Meanwhile, United are preparing to face local rivals Manchester City on Monday.