John Danaher was born in 1967 in Washington, DC, United States, to New Zealand parents. Shortly after his birth, his family relocated back to New Zealand, where Danaher spent his formative years. This upbringing granted him dual citizenship (USA-NZ). Danaher pursued higher education in philosophy, earning a Master's Degree from Columbia University in New York City.

Danaher began his Brazilian Jiu-Jitsu journey at the relatively late age of 28, while working as a club bouncer in New York City. Initially drawn to grappling for its practical self-defense applications, he attended his first class at the renowned Renzo Gracie Academy. Despite initial skepticism toward grappling arts, Danaher quickly recognized their effectiveness and became deeply committed to training.

Danaher's transition into coaching occurred unexpectedly when prominent instructors Matt Serra and Ricardo Almeida departed from the Renzo Gracie Academy. At the time, Danaher held the rank of purple belt but embraced the opportunity to teach, dedicating himself obsessively to mastering the craft. He spent 12-14 hours daily on the mats, refining his analytical approach to grappling. His unwavering dedication culminated in receiving his black belt on April 2nd, 2002, alongside training partner Shawn Williams.

Danaher is widely recognized for pioneering a systematic approach to leg-lock submissions, significantly reshaping modern no-gi grappling. His instructional frameworks emphasize structured problem-solving and progressive technical sequences, revolutionizing how practitioners approach submissions. Danaher's innovative methods have profoundly influenced a generation of competitors and coaches.

As a coach, Danaher assembled an elite group of grapplers known as the Danaher Death Squad, featuring notable athletes such as Gordon Ryan, Garry Tonon, Eddie Cummings, Craig Jones, Nicky Ryan, and Oliver Taza. The team gained widespread acclaim for their aggressive, submission-oriented competition style. However, internal conflicts and logistical challenges led to the team's disbandment in July 2021.

Following the dissolution of the Danaher Death Squad, Danaher co-founded the New Wave Jiu-Jitsu academy in Austin, Texas, alongside his star pupil Gordon Ryan. The academy provides an elite training environment emphasizing both no-gi and gi disciplines. Expanding his coaching repertoire, Danaher began guiding gi competitors, notably assisting gi world champion Nicholas Meregali in both gi and no-gi preparations.

Danaher integrates his academic background in philosophy into his coaching methodology, viewing grappling challenges as "problems to be solved" rather than obstacles to overcome through brute force. He advocates the "Kaizen" philosophy of continuous incremental improvement, regularly sharing insights on training, mindset, and technique through social media and podcasts. His analytical and philosophical approach has significantly impacted the broader Brazilian Jiu-Jitsu community.

Between 2023 and 2024, Danaher underwent multiple surgeries, including hernia, hip, and knee replacements. Due to these health challenges, he announced the possibility of stepping back from high-level coaching during his recovery period. Danaher has indicated a potential shift toward recreational jiu-jitsu instruction, marking a new chapter in his coaching journey.

Beyond Brazilian Jiu-Jitsu, Danaher has significantly influenced mixed martial arts (MMA), notably coaching UFC champion Georges St-Pierre. His effective application of grappling principles within MMA contexts has shaped the broader combat sports landscape, solidifying his reputation as one of the most influential grappling coaches in MMA history.