Coached by Paul Green and co-captained by Johnathan Thurston and Matthew Scott, they competed in the NRL's 2015 Telstra Premiership.
The Cowboys celebrated 20 years as a club in 2015 and played in the first all-Queensland grand final, defeating the Brisbane Broncos 17–16 in golden point to win their first premiership.
The Cowboys finished in 3rd place, winning 17 games, giving the club their most successful regular season in its history.
The 2015 competition was played over two days on January 31 and February 1 at Eden Park in Auckland, New Zealand.
The Cowboys featured in the Waiheke pool and played Melbourne, Penrith and South Sydney.