In a large mixing bowl, combine the shredded cabbage and grated carrots. Toss them together until evenly mixed.
In a separate bowl, whisk together the mayonnaise, apple cider vinegar, sugar, celery seed, salt, and black pepper until smooth and well combined.
Pour the dressing over the cabbage and carrot mixture. Toss everything together until the vegetables are fully coated with the dressing.
Cover the bowl with plastic wrap and refrigerate for at least 1 hour to allow the flavors to meld. For best results, chill for 2-4 hours.
Before serving, give the coleslaw a good stir and adjust seasoning if necessary.