The Norwegian had already tasted success in the 7.5km sprint, as well as three relay titles, and she got the better of World Cup leader Dorothea Wierer to finish her time in Antholz-Anterselva on a high with a fifth gold.
Roeiseland finished 20.7 seconds clear of Wierer, her two targets missed to the Italian's three, proving the difference.
Sweden's Hanna Oeberg also missed three as she came home 26.1 seconds behind the Norwegian.
With this victory, Roeiseland is up to fourth in the World Cup standings, but Wierer was able to stretch her lead over Oeberg to 106 points.
Oeberg is up into second as she moves in front of Tiril Eckhoff who could only manage seventh in the mass start.
Highlights: Roeiseland obliterates rivals