Demi Lovato wants her fans to “stand up” for a good cause.

The 21-year-old pop star is promoting a “revolutionary global movement” called unite4:good, and she took to Twitter on Monday hoping to get fans involved.

“What do you stand 4? Stand up 4 a good cause + make a pledge on behalf of @Unite4good in honor of #u4gunite4humanity,” she wrote.

Unite, founded by philanthropist Anthony Melikhov in 2013, promises to connect individuals with a variety of organisations in need of assistance to “ignite positive and lasting change on a global scale”.

According to the website, part of their mission is to “establish a new standard whereby acts of kindness and service become so valued and celebrated that people make them a part of their daily life”.

Demi proved her words of support weren’t empty at the weekend, when she made a few of her young fans smile during a trip to Levine Children's Hospital in Charlotte, North Carolina.

The visit was part of an effort organised by the Ryan Seacrest Foundation.

A spokesperson for the US TV host’s non-profit took a moment to share a picture of Demi smiling with one of her young fans via Twitter on Sunday.

“@ddlovato you stopping by @RyanFoundation inspires our kids to be warriors everyday!! Thx for taking the time d :),” the rep tweeted.

“Anytime!!! Xox,” she replied.

Demi is currently on the road performing her Neon Lights World Tour, which is travelling to Sunrise, Florida for a show on Tuesday.

The trek is scheduled to wrap on May 17 in Monterrey, Mexico.