The "Rehna Hai Tere Dil Mein" star will take forward the message of the government's 'Swachh Saathi' programme, which she hails as the most important part to realise the dream of a clean country.
"Swachh Bharat is among the most important initiatives taken up by the government and I believe that the Swachh Saathi programme will be an extremely important part of our dream to realise a clean, healthy and environmentally conscious youth and country," Dia, 34, said in a statement.
"Dia is a youth icon and has been an active campaigner for Swachh Bharat. We felt that she would be the best person to help us reach out to more youngsters. Our aim is to make it a viral youth led movement," Swachh Bharat mission director Praveen Prakash said.
As the ambassador, the actress would interact with school and college students from across the country through awareness sessions, community cleaning activities and motivational videos.