In 2004, the couple established the Reinhard and Sonja Ernst Foundation, which pursues exclusively and directly the promotion of charitable purposes. The Ernst couple focus primarily on the following charitable purposes: the promotion of art and culture, the education and support of children and young people in need, assistance for the elderly worldwide, support for development aid and the preservation of historical monuments.

One project that has already been realized is the "House of Encounter" in Natori in Japan, which became a new meeting place for many children and old people after the tsunami disaster in 2011. The world-famous architect Fumihiko Maki, a friend of the couple, took on the planning and construction management. The center is operated by the municipality.

The construction of a music school building in Eppstein, which was handed over to the town of Eppstein in 2016, was another project of Mr. and Mrs. Ernst, who believe that musical education is extremely important for society and that music schools are necessary to promote and develop the personal development of pupils.

Another outstanding project for the state capital of Wiesbaden was the planning and construction of the "Museum Reinhard Ernst" (mre) in Wiesbaden. The museum for the exhibition of the couple's artworks was opened on June 23, 2024.

The Japanese architect Fumihiko Maki was also commissioned with the construction. Today, the museum (approximately 6,000 square meters of land, 9,700 square meters of floor space and around 2,200 square meters of exhibition space) is unparalleled: 970 paintings and sculptures from the field of abstract art delight visitors. These include countless school classes, who can visit the exhibition free of charge in the morning to gain access to modern art. The museum team wants to make art accessible to everyone.

Another project being planned is a residential and nursing home for senior citizens in Wiesbaden-Naurod, financed by the foundation, which will provide 90 to 100 senior citizens with accommodation, care and nursing.

Mr. and Mrs. Ernst do outstanding work for society and especially for the state capital of Wiesbaden. They inspire and initiate and are role models who invite imitation. They are down-to-earth visionaries who have crowned their life's work with the construction of the mre in Wiesbaden.

The museum, which will open in 2024, has given the international art scene a museum of international standing. "This building belongs to art, and art belongs to everyone" is the Ernst couple's motto in the museum foyer, which anyone can enter free of charge - an invitation to the urban community and a fitting expression of Sonja and Reinhard Ernst's philanthropic work.