The ground was opened in 1890 and the pitch had not been overhauled since 1963 when undersoil heating was installed, said the rugby league club.
Work is to start in October to dig out the old playing surface to a depth of 18in (450mm) and is due for completion in December.
The ground is to be used as a venue for the Rugby League World Cup in 2013.
The stadium complex is also home to Yorkshire County Cricket Club and rugby union team Leeds Carnegie.
The rugby posts are currently concreted in place and are to be replaced by a set that can be removed easily.
Gary Hetherington, Leeds Rhinos chief executive, said the work was a "considerable investment" but would attract more events to the stadium.
The head groundsman, Jason Booth, said the club had considered an artificial surface but a reinforced grass pitch was the "right option".
The club's chaplain, the Reverend Steve Mitchell, is to hold a service of remembrance on the pitch before the work, for those who had their ashes scattered at the ground.
The Headingley stadium in Leeds is to get a new rugby pitch in a £1m project, says team Leeds Rhinos.