Viikki (Swedish: Vik) is a neighbourhood of about 5,500 inhabitants in Helsinki, Finland. It is located at the bottom of Vanhankaupunginlahti bay, some 7–10 km from the city centre.

The district hosts the Viikki Campus with four of the faculties of the University of Helsinki (biosciences, pharmacy, veterinary medicine, and agriculture and forestry) as well as other university units such as research centres, science library and teacher training school.

Viikki is known for its natural environment. The conservation area of Vanhankaupunginlahti is an important place of nesting and migration for birds. Large fields and farmlands are cultivated by a teaching farm that is part of the university's agricultural faculty. Southernmost part of the Latokartano residential zone is known as an "ecological housing" area. Many apartment buildings there have, for instance, experimental solar and wind energy systems installed.

Viikki is divided into the sub-areas of Viikki science park, Latokartano, Viikinranta and Viikinmäki. In the 2000s the population of the district has increased steadily. This is because some areas of Viikki — especially in Latokartano and Viikinmäki — have been among the most important sites in Helsinki for the construction of new apartments. By 2015, the total population of the district is expected to be around 15,000.