Danone, which has not disclosed a fee for the deal, said it was attracted by Aqua d'or's 30 per cent sales growth in 2005. The company is number one in bottled water in Denmark and number two in Sweden.
The move sees Danone branching out in Western Europe after struggling with bottled water sales in France.
The group said Scandinavia offered significant potential because bottled water consumption there averaged 22 litres per person, compared to 110 litres in Western Europe overall.
"This partnership with Aqua d'or, the local fastest growing bottled water company, will allow Groupe Danone to benefit from its knowledge of the market as well as the distribution channels in the Nordic region," said Franck Riboud, Danone chairman.
Allan Feldt, Aqua d'or chairman and founder, said his firm would do its best to make Danone's Evian brand the biggest bottled water import in Scandinavia.
Danone's beverage sales have struggled in Europe recently, largely due to disappointing performances from top water brands - Evian and Volvic - in France. Competition in Europe's bottled water sector has intensified as more drinks firms have looked to target consumer health trends, yet consumption, already high, has not kept up in all regions.
Danone said recently that new products, such as mini Evian bottles and a functional tea drink under the Taillefine brand, were starting to pay off.
But, there were signs the firm may also use acquisitions to relieve the pressure.
Antoine D'Estaing, Danone's chief financial office, told the Wall Street Journal the group was looking to spend up to €1bn on small to medium businesses in new, emerging markets over the next three or five years.