Picnic in the City featured musicians and an open-mike forum for people to share their thoughts.
Organiser Marcia Cassidy said the day was about promoting talking together and "creating a forum where people can ask questions about what's going on in the country".
It was important for people to learn about the history of New Zealand and the Treaty of Waitangi, as well as celebrate as a community, no matter what their ethnic background, she said.
Fellow organiser Pip Laufiso said it was important to share information about the treaty, why and how it was signed, what impact it had, and why it was still relevant today.
"The majority of young people go through our education system not knowing about the treaty," she said.
She was also "proud" Dunedin Mayor Dave Cull continued the tradition of flying the Tino rangatiratanga flag on the Civic Centre.
Musician and activist Tigilau Ness travelled from Auckland to be part of Picnic in the City.
It was the first time he had performed in Dunedin and said the day was all about "one love".
"It's wonderful to be in this part of Aotearoa New Zealand on our special birthday," he said.
