Kids were separated into their year levels and counted down at the start line. Year 8 children went first with each year level following them until the 5-year-olds set off.
Mum Catherine McBeth was at the marathon finish line cheering on her son Benjamin, 12.
She said her children loved anything to do with getting outside and being active.
"This year it was just [Benjamin] taking part but all the kids love this kind of thing and are keen to take part."
Benjamin said it was his third time taking part in the event.
"It's a lot of fun. We do most of the trainings at school in the lead up to this event and then we get to finish off on the actual Rotorua Marathon course - It's pretty cool and gives you a bit of a thrill."
Rebecca Annabell had two children taking part in the challenge.
"They were pretty eager to do it and get it done. They're willing to give almost anything a go."
She said most of their trainings happened at school and "took a bit of motivating" but her children still enjoyed it.
The event was organised as a collaborative project between Event Promotions, Events and Venues, Athletics New Zealand and Sport Bay of Plenty, with the aim of giving more primary school children a taste of the benefits of staying fit and healthy.
Each participant received a Certificate of Completion and the opportunity to take home a spot prize to acknowledge the significant effort from the children.