About three hectares of agricultural land to the east of the present site will be taken over to boost capacity from 470 vehicles to around 1000.
The plans also include the realignment of Riccarton Mains Road, to follow the outer boundary of the extension, and the creation of a new roundabout.
Landscaped strips will screen the car parking area from the road and adjacent fields. Hermiston is the busiest of Edinburgh’s park-and-ride sites. The number of vehicles using the site has increased from 50,000 in 2005-06 to 100,000 in 2010-11.
A public consultation on the proposed expansion of the site was held in August last year.
A report by planning officials said although the site is in the green belt, the impact of park-and-ride sites in reducing congestion and pollution in the city justified the extension.
The report recommends approval of the plans by the council’s development management sub-committee.