Preheat the oven to 400F, rack in the middle. Line a large rimmed baking sheet with foil ensuring the foil goes up and over the sides.
Add the green beans to the pan.
Cut the potatoes into 1/2” cubes and place on the sheet pan spreading the beans and potatoes in a single layer. Drizzle the veggies with olive oil. Sprinkle on the salt, garlic powder and smoked paprika.
Roast for 25 minutes. While the veggies are roasting, slice the kielbasa on an angle 1/2” thick.
Remove from the oven, turn the veggies (If the potatoes start to stick, leave them be). Add the kielbasa on top. Return to the oven and bake for 25 minutes.
Remove from the oven, flip over the kielbasa and bake for 5 more minutes.
Remove from the oven, taste for seasoning and enjoy!
Store any leftovers in an airtight container in the fridge.