The thousands of people expected at the Raggamuffin festival in Rotorua tomorrow are being promised a good time by one of its headliners.

Around 30,000 people are expected to attend the concert at Rotorua Stadium, which features reggae, R&B and hip hop stars, including Lauryn Hill, Ben Kingston and Shaggy.

Shaggy performed at Raggamuffin last year and says it coming back was not a hard decision, as it is a great audience and vibe. The Boombastic and It Wasn't Me singer says he will be getting the crowd jumping again this year.

"We're gonna rock the house. And wear comfortable shoes cause you will be on your feet all day dancing."

In true Shaggy style, he also commented on how beautiful New Zealand women are.

Organiser Leesa Tilley says Raggamuffin has exploded in size since its inception in 2008.

"We've extended the space inside the stadium to double the size of the first year to incorporate a whole 50 or 60 different stalls and a kids zone and we've got a second buskers' stage."

Ms Tilley says they never expected the event to get so big so fast. She believes its success comes from keeping things simple.

"Just a nice and relaxed vibe. There's only one main stage so people can kinda grab a place on the grass, or a seat, and then sit there for the entire day."