Preheat your oven to 400°F and line a large baking sheet with parchment paper for easy cleanup.
Slice the baby potatoes into halves and trim the tough, woody ends off the asparagus spears.
In a small bowl, whisk together the olive oil, lemon juice, lemon zest, minced garlic, rosemary, salt, and pepper.
Arrange the chicken breast, halved potatoes, and asparagus on the prepared baking sheet in a single layer.
Brush the lemon-herb marinade generously over the chicken and toss the vegetables until they are well-coated.
Roast in the oven for 20 to 25 minutes, or until the chicken is cooked through and the potatoes are golden and tender.
Allow the chicken to rest for several minutes to lock in the juices before slicing and serving warm.