Kaylee peaked in U.S. baby name data around 2003-2008, which means it's now predominantly a Millennial name — the generation currently most likely to own a dog. Some of those owners are naming their pets after people they grew up with, or choosing a name that simply sounds familiar and warm from their own childhood landscape. Female pets named Kaylee skew heavily toward the companion and family dog breeds.
The Millennial Name Ecosystem
Kaylee belongs to the same naming generation as Kaitlyn, Brittany, and Ashley — high-frequency names of the late 1990s and early 2000s that now read simultaneously as dated (for baby naming) and warm (for pet naming). That temporal shift is a genuine phenomenon: names that peak in human use often show up on pets a decade or two later, carried by owners who have a personal affection for the sound from their own cohort. Golden Retrievers and Labrador Retrievers appear in this name's registry data most often.
The Firefly Reference
Kaylee Frye from the TV series Firefly (2002) gave the name a specific sci-fi-geek association that some owners are directly referencing. The character is warm, mechanically gifted, and enthusiastically good-natured — not a bad personality template for a beloved dog.
Counter-Read
Kaylee's Millennial-era peak makes it feel slightly generationally specific in a way that, say, Lucy or Bella do not. If you want a name without that timestamp, compare Callie or Kaia for similar sounds with different cultural timing.