At the end of his debut season Brown played for the St. George Dragons in the 1993 Winfield Cup Grand Final loss to the Brisbane Broncos.

Brown played for the newly formed St. George Illawarra Dragons at hooker in their 1999 NRL Grand Final loss to the Melbourne Storm.

During his first season, at a match on Sunday, 13 April 2003 against Manly at WIN Stadium, a frustrated Nathan Brown berated captain Trent Barrett, Brett Firman and Lance Thompson on the sideline in the 53rd minute with the scores locked up at 12-all.

The incident was seen by the crowd and other players on the big screen and proved a decisive turning point as Manly ran in five second half tries to win 38–12.

On 1 April 2008, it was announced that Brown would not coach St. George Illawarra in the 2009 season, which ended an association with the club that stretches back to the start of the joint venture.

[9] In his second season, Brown guided St Helens to 1st place in Super League and victory in the Grand Final, after defeating the Wigan Warriors 14–6 at Old Trafford.

Based in Sydney, Brown worked on scouting assignments and provided specialist coaching for the club's hookers.

In round 7 of the 2022 NRL season, New Zealand suffered their heaviest ever defeat losing 70-10 against Melbourne at AAMI Park.

Brown and the Warriors agreed to part ways immediately after he informed the club he would not be able to relocate his family to New Zealand for the long-term.

[29] In November 2024, Brown re-joined Parramatta signing on to be the assistant head coach ahead of the 2025 NRL season.