There are 12 rugby clubs from Mahurangi RFC, based in Warkworth, Rodney District, in the north through to Massey the southernmost area of the union.

It competes in the Mitre 10 Cup, the successor to New Zealand's former domestic competition, the National Provincial Championship (NPC).

North Harbour has enjoyed a great deal of success on the rugby field having produced All Blacks and other New Zealand representative players, and also winning the 3rd division title in their first year, then promotion to NPC Division 1, and making the finals of the NPC competition on several occasions during the 1990s, including hosting the 1994 final at a capacity-crowd Onewa Domain against Auckland and qualifying for the Super 10 competition in 1993, 1994 and 1995.

2009 was the same with North Harbour finishing 12th, however they defeated the champions Canterbury 22–19 in the opening round and beat Auckland 16–14 at Eden Park.

2014 was downfall for North Harbour, as they only won 3 games, against Manawatu (24-13), Canterbury (29-24) and Hawkes Bay (28-25) 2015 seemed the same for North Harbour, they won 3 games again, against Southland (26-25), Counties Manukau (28-20) and Northland (36-12) 2016 saw North Harbour get promoted up from the Championship division, beating Counties Manukau (20-17), Manawatu (29-25), Southland (35-14), Bay of Plenty (44-34), and Northland (44-28),They defeated Wellington in the semi-final (40-37) and defeating Otago to be promoted to the 2017 Premiership (17-14) In 2017, North Harbour won a lot of their games, beating Otago (19-17), Southland (45-20), their greatest Battle of the Bridge win against Auckland (57-10), Counties Manukau (27-18), Northland (22-31), Hawke's Bay (33-30), Waikato (13-11), They made the semi-finals but did not beat Canterbury (35-24 loss) 2018 saw North Harbour beat Northland (21-20), Waikato (28-29), Bay of Plenty (32-30), Hawke's Bay (34-51), Taranaki (26-55), Counties Manukau (36-26).

North Harbour succeeded in their eleventh challenge for the shield on 24 September 2006 by beating the previous holders Canterbury 21–17 at Jade Stadium in Christchurch.

[5][6] After defeating Taranaki 19–13 in their first challenge in the Air New Zealand Cup, North Harbour lost the Ranfurly Shield to Waikato by a record margin of 52–7.

The premier title is fought for among senior teams for the right to be crowned North Harbour Club Rugby Champions.

North Harbour's other Major Partners are: - Go Media (Principal Partner) - CMP Construction - NHR Group - Merlin - Exedy - Kennards Hire - North Harbour Ford - Barfoot & Thompson - McDonald's - Gallagher Insurance - Benefitz