A car is effectively essential. The beach strip is about 17 miles long and spread out in a way that makes walking between places impractical. Most accommodation includes parking, but in peak summer season the parking situation at popular spots — St. Andrews State Park, in particular — fills up early. The park operates a first-come, first-served policy and regularly hits capacity by mid-morning on busy days.
The Emerald Coast Connector shuttle runs along the beach road in summer, connecting major stops from Pier Park east to St. Andrews State Park. It is inexpensive and air-conditioned, and useful if you're staying close to the shuttle route. Rideshares work well within the strip but surge badly on weekend nights.
Bicycling the length of the strip is possible on the multi-use path but requires tolerance for heat and distance. Bikes and golf carts are available for rent from various outfitters.