I went through the Pinterest design loop last fall for a senior IC role. Sharing because design interview breakdowns are weirdly rare compared to SWE write-ups.
First thing to know: Pinterest has strong design opinions. They care about visual quality AND systems thinking AND user insight. You need all three. If your portfolio is strong on craft but you can't talk about user problems in structured, evidence-based terms, you'll get filtered. If your portfolio is all process and weak on the final output, also a problem.
Portfolio screen (45 min) One recruiter, sometimes joined by a design manager. They'll ask you to walk through 1-2 projects. Pick work that shows: a real constraint, a messy middle phase, a concrete decision you made and why, and an outcome. Don't over-polish into a case-study teleprompter. They ask follow-up questions and they can tell when you're reciting versus remembering.
For Pinterest specifically: consumer-facing work reads better than pure enterprise. They want to see you think about emotion and delight, not just task completion.
Design challenge (1 week, take-home) Mine was a prompt around improving content discovery. Nothing said "build a Pinterest feature" but the domain was relevant. They gave a user research brief and some constraints. I spent about 8 hours total. The deliverable was a Figma deck: problem framing, explorations, final concept, rationale.
Things they cared about in the debrief: why I narrowed to this solution over alternatives, accessibility decisions, what I'd validate first. Not pixel-perfect. They want thinking.
Design critique round They showed me an existing interface (not Pinterest, but a consumer app) and asked me to critique it. Structure this out loud: identify the user goal, what's working, what's creating friction, what you'd change. They're watching how you organize a critique, not just whether you spot the obvious issues.
Cross-functional round Half design, half collaboration. Expect questions like: how have you pushed back on product direction, how have you worked with eng constraints, how do you involve research when timelines are short.
Overall it was one of the more substantive design loops I've been through. They take design seriously as a function, which isn't universal.