Preheat your oven to 425°F and line a large baking sheet with parchment paper.
In a large bowl, toss the green beans and mushrooms with olive oil, minced garlic, salt, pepper, and thyme until everything is evenly coated.
Spread the vegetables in a single layer on the prepared baking sheet, making sure not to overcrowd them.
Roast for 20-22 minutes, stirring halfway through, until the green beans are tender with crispy tips and the mushrooms are golden brown.
Remove from the oven and serve immediately while hot and crispy.