Its music line-up, made up of artists from Auckland and Wellington, includes Terracotta Cat, Bailey Wiley, Womb, Randa, and Trip Pony, as well as a special guest MC.
Exhibiting artists at the party include Lane Park, Sofia Drescher, Connie McDonald, Georgette Brown, Random, Erika Pearce, Jonny4Higher, Chris Hutchison and Courtney Fort Davis.
The other Block Party - the multi-stage hip-hop festival, takes place on Friday, May 20.
The Lady of Rage - known for her collaborations with Dr Dre and Snoop Dogg - has recently joined the line-up which also includes hip-hop greats Bone Thugs-N-Harmony and Twista.
Also on the line-up is Mobb Deep, Tha Dogg Pound, DJ Quik, Che Fu and the Krates, Tomorrow People, PNC, Times x Two, J Williams, K One, DJ CXL, Ill Semantics, Mikey Mays, Giantkilla, Bkidd, and DJ Spell.
Doors to the R18 event open at 5pm with a wrap time of 11pm. Tickets are available from TheTicketFairy, priced between $119 and $219.