Heat the oven and prep the pan.
Preheat the oven to 400°F and line a large sheet pan with foil for easier cleanup.
Cut everything to size.
Slice the chicken thighs into bite-size pieces and cut the broccoli into florets. Keeping the pieces fairly even helps them cook at a similar pace.
Season the chicken.
Toss the chicken with teriyaki sauce and garlic powder until coated.
Season the broccoli.
In a separate bowl, toss the broccoli with olive oil, salt, and black pepper.
Arrange on the pan.
Spread the chicken over one half of the pan in a single layer and place the broccoli on the other half. Scatter the pineapple over the chicken side.
Roast until done.
Bake for about 20 minutes, or until the chicken reaches 165°F and the broccoli is tender with browned edges. The source notes checking around the 15-minute mark in case your oven runs cool or hot.
Rest briefly and serve.
Let the pan rest for 2 to 3 minutes so the glaze settles a bit, then serve everything warm with the pan juices spooned over the top.