I applied to their online website and a few days later I had a call from Head Office. They gave me an phone interview (they ask you about your previous jobs, why should you work at H&M, what you know about the company, etc.) and told me that I had to go to an interview at the store.
I went there, 15 minutes early and they told me to wait. They forgot to tell the manager I was there (those things happen, I wasn't mad or anything). It took a while before they were ready, but they apologized to me. Afterwards, they talk about themselves (they were two) and I did so, they asked about my previous job, about me, what I like about H&M, what I know about the company (SUPER IMPORTANT), what I would do in certain situations, etc. They told me I would likely be called back for a second interview.
The day after, I got a call from one of the girls who interviewed me. I had the second interview the week after. I got to the store again and they asked me practically the same questions, but asked me in which department I would like to work best and what were my availabilities. It was still a 2:1 interview. They told me I would be called back during the week, even if I didn't get the job.
An hour or two later, I got a call from the girl of the first interview and told me I got the job and was starting at the end of the week.