The 24-year-old watched last night’s Europa League defeat by Birkirkara from Tynecastle’s main stand before signing his contract. The move will be completed once international clearance arrives.
Johnsen carries both American and Norwegian citizenship and spent last season with the Bulgarian club Litex Lovech. He has also played in Portugal, Spain and Norway.
He arrives to compete with Conor Sammon, Juanma Delgado and recent loan signing Tony Watt for places up front at Hearts.