Rosmin began his career in 2000 with the Brunei team that was playing in the Malaysian league system. He played for Brunei FA until 2005, joining the club side DPMM FC which replaced Brunei's spot in the Malaysia Premier League. When DPMM moved to the Singaporean league in 2009, he lifted the League Cup as captain after slotting home the winning penalty in the final. He was released after the season ended abruptly due to a FIFA suspension of Brunei, and promptly joined MS ABDB where he won the domestic FA Cup in 2010. That season, he ended QAF FC's 34-game unbeaten streak by scoring two goals in the penultimate game of the 2009-10 Brunei Premier League, although QAF FC were already champions by then. Rosmin returned to DPMM as club captain in 2012 after their re-entry into the S.League. Since then they have repeated their League Cup success in 2012 and 2014. On 21 November 2015, Rosmin lifted the S.League championship trophy for the first time in DPMM FC history, after a 4–0 win over Balestier Khalsa clinched the title for the Bruneian outfit. After two spells and 11 years of service, DPMM made an announcement on their website on 6 February 2018 that Rosmin will not be retained for the 2018 S.League season.
International career
Rosmin made his international debut for Brunei at the 2004 AFC Asian Cup qualification which was held in Maldives. He played the full 90 minutes in a 1–1 draw against the home team on 21 March 2003. He also played against Myanmar two days later in a 5–0 loss. Rosmin's next international appearance was at the 2012 AFF Suzuki Cup qualification held in Myanmar, where he captained the side to two wins out of four. He also led the team in the 2014 tournament in Laos, where Brunei lost all their games. Rosmin was made captain of Brunei for the 2016 AFF Suzuki Cup qualification matches that was played in Cambodia in October 2016. He did not start the first game against Timor-Leste as Mike Wong opted for Nur Ikhmal Damit and Shahrazen Said in the central midfield roles, and only came on at right-back to replace Fakharrazi Hassan later in the game which finished 2–1 in favour of the Wasps. He did not retain the captain's armband from Faiq Bolkiah despite starting the game at left-back against hosts Cambodia in a 0–3 loss. Rosmin was finally played in central midfield in the final game against Laos where Brunei fell again to a 4–3 scoreline. It is reported that the 2016 AFC Solidarity Cup held in nearby Kuching, Malaysia would be Rosmin's last competition as an international footballer. He started the first game as captain in an emergency centre-back role and led the team to a 4–0 victory over Timor-Leste, Brunei's biggest ever win to date. He reprised the role in the semi-final against Macau, but after playing for over an hour at 1–1 with only 10 men, he missed his spot-kick in the ensuing penalty shootout, which Brunei would eventually lose 4–3. He played his final match for the Wasps in a 3–2 loss at the hands of Laos in the third-place play-off on 14 November.
Rosmin is affectionately called "Bobby" by his teammates and fans. His brother Rosaidi Kamis was also a footballer, who was with the Brunei team that won the 1999 Malaysia Cup. His sister Rosita is a lawn bowler who has won medals for Brunei.
