Janez Andrejašic (born March 26, 1943 in Ljubljana) is a Yugoslav retired slalom canoeist of Slovenian nationality who competed from the early 1960s to the mid-1970s.
He won a silver medal in the C-2 team event at the 1965 ICF Canoe Slalom World Championships in Spittal with Jože Gerkman, and finished sixth in the C-2 event at the 1972 Summer Olympics in Munich with Peter Guzelj.