The Navarrese right-back posted his farewell message on social media, saying the emotions of writing it had proved more difficult than he had anticipated despite feeling mentally prepared for the moment.
"When I first started kicking a ball as a child in Pamplona with my schoolmates, I never imagined the incredible journey that lay ahead of me."
He acknowledged the difficulty of finding the words to do justice to two decades of professional football.
"Despite being psychologically ready to take this step, it has been very hard to write this goodbye to the pitches."
Azpilicueta's career was defined by longevity, leadership and a capacity to adapt to different systems, coaches and cultures.
He joined Osasuna's academy as a teenager, made his senior debut with the Pamplona club and moved to Olympique de Marseille before his most celebrated chapter at Chelsea, where he won the Champions League, the Europa League twice, the FA Cup and the League Cup during 11 years at Stamford Bridge.
After leaving Chelsea, he joined Atletico Madrid and subsequently moved to Sevilla, representing Spain at four European Championships and two World Cups across a senior international career that brought 35 caps. He was part of the Spain squad that won Euro 2008 as a young squad member, though his contributions to the first team came primarily across the following decade.
Azpilicueta is regarded within the game as the archetype of the modern right-back — consistent, technically reliable, intelligent positionally and an exemplary professional in his approach to training and leadership. His farewell was received across the European game with an outpouring of tributes reflecting the respect he accumulated across 20 years and six clubs.