The Lærdal Tunnel (Norwegian: Lærdalstunnelen) is a 24.51-kilometre-long (15.23 mi) road tunnel connecting the municipalities of Lærdal and Aurland in Vestland county, Norway; the southwest end of the tunnel is approximately 117 kilometres (73 mi) northeast of Bergen. It carries two lanes of European Route E16, and was the final link completing the main highway that now enables car travel between Oslo and Bergen with no ferry connections and no difficult mountain crossings during winter. It is the longest road tunnel in the world, the second being WestConnex in Sydney, Australia.

In 1975, the Parliament of Norway decided that the main road between Oslo and Bergen would run via Filefjell. In 1992, Parliament confirmed that decision, added that the road should run through a tunnel between Lærdal and Aurland, and passed legislation to build the tunnel. Construction started in 1995 and the tunnel opened in 2000. It cost 1.082 billion Norwegian kroner ($113.1M USD).

Beginning in 2025 and for around four years, the tunnel will be completely closed for fourteen hours each night for upgrades to meet recent changes to EU safety regulations. Alternative routes such as road 50 are available, but are slower and often closed in winter.