Add the chopped chicken, broccoli florets, pesto, and sun-dried tomatoes to a large zip-top bag; seal and shake until everything is evenly coated in pesto.
Refrigerate and marinate for at least 1 hour, or up to 24 hours for more flavor.
When ready to cook, heat a large non-stick skillet over medium-high heat and add the marinated mixture to the hot skillet.
Stir the ingredients into an even layer and let sit undisturbed 2–3 minutes to brown the chicken, then stir and brown another 2–3 minutes.
Cover the skillet with a lid and cook, stirring occasionally, until the chicken is cooked through and the broccoli is tender, about 10–15 minutes total.
If a lot of liquid accumulates, uncover and allow it to simmer off so the sauce thickens.
Taste and add sea salt as needed, then serve warm.
