The two projects, located in Bac Gia Nghia Ward, cover a combined area of more than 24.1 hectares and cost nearly VND 525 billion (USD 20 million) in state funding.
Gia Nghia Central Square, set beside a lake and integrated with a commercial centre, is among Vietnam's 10 largest public squares and the largest in the Central Highlands and south-central coastal region.
The adjoining museum-library-park complex is designed to support cultural, educational and recreational activities while providing a venue for major political, economic and cultural events.
Provincial Chairman Ho Van Muoi said the projects would improve urban infrastructure, create new community spaces and support tourism, trade and investment.
Residents and visitors attended an arts programme and light show after the inauguration ceremony on Saturday evening.
Lam Dong also opened a trade fair featuring local agricultural products, specialities and goods certified under the One Commune One Product programme.