Viking Line’s history can be traced back to 1959, when a group of sea- and businessmen from the Åland Islands province in Finland formed Rederi Ab Vikinglinjen, purchased a steam-powered car-ferry SS Dinard from the UK, renamed her SS Viking and began service on the route Korpo(Finland)–Mariehamn (Åland)–Gräddö (Sweden). In the same year the Gotland-based Rederi AB Slite began a service between Simpnäs (Sweden) and Mariehamn.
In 1962, a disagreement caused a group of people to leave Rederi Ab Vikinglinjen and form a new company, Rederi Ab Ålandsfärjan, who began a service linking Gräddö and Mariehamn the following year.
Soon the three companies, all competing for passengers between Åland Islands and Sweden, realised that they in the long run all stood to lose from mutual competition. In 1965 Vikinglinjen and Slite began collaborating, and in the end of July 1966 Viking Line was established as a marketing company for all three companies. At this time Rederi Ab Vikinglinjen changed their name to Rederi Ab Solstad, in order to avoid confusion with the marketing company. The red hull livery was adopted from Slite’s Ålandspilen service (to which it had been taken from the colour of the chairman’s wife’s lipstick!). In 1967 Rederi Ab Ålandsfärjan changed its name to SF Line and in 1977 Rederi Ab Solstad was merged into its mother company Rederi Ab Sally.