Pinkie Pie is based on the G3 pony of the same name. The G3 pony's coat is pink, with her mane and tail a lighter shade, and her cutie mark is three balloons with curved strings. The current Pinkie Pie's cutie mark matches that of a Pegasus pony from G1, Surprise. Lauren Faust had published concept art of Surprise which bears a strong resemblance to Pinkie Pie, only with a white and yellow color scheme and Pegasus wings, and Hasbro published a recolor of the image in their "Style Guide for Pinkie Pie", complete with Pegasus wings. Pinkie Pie ultimately remained grounded and her wings were given to Fluttershy, who was back then called Posey.

Pinkie's hair "poofing up" when she's happy and going flat when she's sad was conceived by Jim Miller for The Cutie Mark Chronicles, and repeated in future episodes by James Wootton.