In 1978, Brig Gen (R) Dato’ Hj Rosni’s military journey began at Pusat Latihan Darat Angkatan Tentera Malaysia (PULADA). Over the years, he immersed himself in various military courses, becoming a versatile officer. In 1981, he became a Helicopter Pilot, serving at No.10 Kuala Lumpur Air Base Squadron and later at No.7 Kuching Air Base Squadron, where he undertook daring missions, including Search and Rescue and VIP transport.

Beyond flying, Brig Gen (R) Dato’ Hj Rosni became a Flight Instructor, Staff Officer, and Intelligence Officer, constantly expanding his knowledge through international courses. He even served as the Defence Attaché to the Sultan of Pahang, contributing to the community’s welfare. Returning to the Royal Malaysian Air Force (RMAF), he commanded squadrons, managed bases, and piloted VVIP/VIP figures. Later, he played a vital role in shaping the Air Operations Division of the Malaysian Maritime Enforcement Agency (MMEA).

Throughout this journey, Brig Gen (R) Dato’ Hj Rosni forged lasting relationships with influential figures in government and aerospace, leaving an enduring mark on aviation and military service. His life is a testament to dedication, versatility, and an unwavering pursuit of excellence.