De Stijl, when applied to architecture, is most generally associated with J.J.P. Oud, Gerrit Rietveld, and Robert van’t Hoff. Though De Stijl was only active for about 15 years, until Theo van Doesburg’s death, the movement is still very noted in both art and architecture. After van Doesburg’s death, though, there was no central administration, the journal came to an end, and the members basically went back to whatever they were doing before. The members didn’t necessarily really know each other; Rietveld famously stated in 1955 that he had never met Piet Mondrian.
Stylistically, De Stijl has everything to do with primary colors and straight lines. By a few sources, Piet Mondrian left the group because of a disagreement with van Doesburg over whether diagonal lines were as vital and fundamental as vertical and horizontal. (Van Doesburg claimed they were, while Mondrian disagreed.)
In this post, I’ll profile each of the three major De Stijl architects and some of their works.
First, Gerrit Rietveld. Rietveld designed the famous “Red and Blue Chair”, which is seen below; for it, he also designed a type of furniture joint that now bears his name. Additionally, Rietveld was responsible for making what some people claim to be the only building that truly expresses De Stijl principles, the Rietveld-Schröder House, in Utrecht. I was unable to find sufficient photos of the inside, so I encourage you to go here and take their video tour. (Alternately, if you’re in the Netherlands, make a reservation and take the real-life tour.)

Red and Blue Chair, Gerrit Rietveld

Rietveld Joint

External picture of the Rietveld-Schröder House, Gerrit Rietveld, Utrecht
J.J.P. Oud is most famous for works in and around Rotterdam, where he served as a municipal architect during the heyday of De Stijl. The most famous work of his that exemplifies De Stijl is the Café de Unie in Rotterdam, seen below. After leaving De Stijl, Oud was part of the Weissenhof Estate Exhibition, where 15 modern architects designed housing. The second picture below is of a row of five townhouses designed by Oud.

Café de Unie, JJP Oud, Rotterdam

Weissenhof Estate housing, JJP Oud, Stuttgart
Robert van’t Hoff designed a bunch of stuff during the early days of De Stijl, before quitting in 1922 to go set up anarchist communities. One of his more famous designs was a houseboat in which he and his wife lived; unfortunately, pictures do not seem to exist of it online. What I can offer you are pictures of a house he designed near Utrecht and a banister post.

Henny House, Robert van't Hoff, Utrecht

Banister post, Robert van't Hoff
I’ll leave you with a Piet Mondrian painting: Composition in Yellow, Blue, and Red.

Composition in Yellow, Blue, and Red, Piet Mondrian
Joseph Beuys (1921-1986) was a German artist who created scenes and “Actions” that addressed social upheaval, change, and human isolation. His work often contained ordinary objects transformed into signs of the human condition and lots and lots of felt. In Coyote: I Like America and America Likes Me, Beuys flew to New York, wrapped himself in felt, and was transported via ambulance (so that he would never touch American soil) to a small room containing a coyote in which Beuys would reside for three days. During that time, he wrapped himself in felt and held a cane, got the Wall Street Journal delivered, and allowed the coyote to interact with him. In doing this Action, Beuys hoped to “isolate myself, insulate myself, see nothing of America other than the coyote.”
Joseph Beuys’ Coyote: I Like America and America Likes Me

Intact felt and wild coyote

Further along in the experiment
The following video is a short excerpt of what is almost an hour of these shenanigans. Enjoy.
