John Mulaney: Baby J (stylised as John Mulaney: "Baby J") is a 2023 stand-up comedy film written by and starring John Mulaney. It was recorded in February 2023 at the Boston Symphony Hall and was released by Netflix on April 25, 2023. It is Mulaney's fifth stand-up special and was released five years after his fourth, Kid Gorgeous at Radio City (2018). The special consists of Mulaney recollecting his life experiences and escapades surrounding his drug addiction, including his intervention and subsequent rehabilitation.

The special received positive reviews from critics, who praised Mulaney's storytelling, honesty and deconstruction of likability, though was criticized by some for the perceived shorthanded approach to the subject matter.

For the special, Mulaney received the Primetime Emmy Award for Outstanding Writing for a Variety Special, and the special as a whole was nominated for the Primetime Emmy Award for Outstanding Variety Special (Pre-Recorded).