The patty will be available in all of Finland's 65 branches until December 27.
According to McDonald's, the 'El Veggo' burger has 'the flavor of salsa', and features the company's soy patty, along with spicy salsa sauce, vegan McFeast sauce, fresh tomatoes, and salad.
The new launch joins McDonald's first vegan burger - the McVegan - which it initially trialed in one outlet in Finland, later rolling it out across the country, and launching it in Sweden.
Earlier this year, it was revealed that the McVegan patty could be making its way into different McDonald's burger builds.
The fast-food giant's Head of Food and Menu Strategy in Sweden, Staffan Ekstam, shared the information with a journalist based in Denmark. According to writer Sidsel Overgaard: "Ekstam even hints that customers may soon be seeing the McVegan patty in other burger builds."