The Gullichsen family home was the world-famous Villa Mairea (1938–39) in Noormarkku, designed by Alvar Aalto, one of the seminal houses of 20th century modernist architecture.
In his early career he did a number of joint works with other architects such as Kirmo Mikkola and Juhani Pallasmaa.
The three partners presented different architectural modernist styles, Gullichsen the monumental, Kairamo the constructivist and Varmola the typological.
The work of the office reached international attention in the late 1970s and early 1980s, described by the British journal The Architectural Review as constituting the "Cool Helsinki School".
Gullichsen's mature architecture can be seen as a late-modernist style, combining the minimalist aesthetic of pure modernism with the humanist touches and concern for locality, craftsmanship and materials derived from Aalto.