Billie Eilish keeps it casual in a red, white and blue look as she headlines Lollapalooza in Chile

Billie Eilish put on a nonchalant display as she resigned Lollapalooza in Santiago, Chile, on Friday.

The 21-year-old singer wore a beanie and an oversized graphic tee that she wore over a long-sleeved top as she took the stage to perform some of her most popular hits at the music festival.

The Happier Than Ever hitmaker also wore a pair of basketball shorts over bright blue leggings emblazoned with stars.

The young musician, about to make her acting debut in Donald Glover’s psychological thriller series Swarm, accessorized with a variety of edgy, silver jewelry.

Lil Nas X, 23, was a showstopper as he also headlined the first night of the three-day festival, and Kali Uchis, 28 – who topped the lineup – put on a standout performance.

Layering: The singer wore a beanie and an oversized graphic tee that she wore over a long-sleeved top as she took the stage to perform some of her most popular hits at the music festival

Star-spangled: The Happier Than Ever hitmaker also wore a pair of basketball shorts over bright blue leggings decorated with stars

For her performance, she opted for a bold and edgy look with contrasting reds and blues.

Eilish pulled on a white racing T-shirt over a red nylon jacket with white and blue stripes on the sleeves.

Matching the royal blue details in her top, she wore shiny blue leggings with white stars.

Over the leggings, the seven-time Grammy winner wore a pair of dark-colored basketball shorts.

The talented songwriter adorned with fingerless gloves that have been snapped up from the cuffs of a pair of white Nike socks.

Eilish styled her jet black fringe and locks in a casual, straight hairstyle under a black beanie with blue flame detailing.

To stomp across the stage, she slipped on a pair of red and blue Jordan sneakers.

For jewelry, she opted for a variety of chunky silver chains around her neck and eye-catching rings on each of her fingers.

She also wore a pair of edgy silver hoop earrings that peeked out from under her raven black hair.

Eilish opted for minimal make-up during the performance to show off her natural beauty.

She looked radiant with a pink blush and a nude lip.

Another protagonist was Lil Nas X, who made his grand entrance in a dramatic and intricate dress with fringes and frills.

Silver statement: The young musician – set to make her acting debut in Donald Glover’s psychological thriller series Swarm – complemented by a variety of edgy, silver jewelry

Grand entrance: Another of the two main acts was Lil Nas X – who made his grand entrance in a dramatic and intricate dress with beaded fringe

Dazzling: The Montero singer and rapper then sheds off the stunning garment to reveal a dazzling white crop top paired with baggy, shimmering pants

Stunning: Uchis wore a white rhinestone studded bustier top and the matching fringed leather microskirt

Monochromatic: The Colombian-American songwriter completed her look with a pair of white over-the-knee boots and styled her long, cascading locks in a high ponytail

Performing Her New Songs: She recently released her third studio album Red Moon In Venus on March 3rd

The Montero singer and rapper then stripped off the gorgeous garment to reveal a dazzling white crop top paired with wide, sparkly pants.

His backup dancers matched his white ensemble in form-fitting bodysuits with several revealing circle cuts and hairy, knee-high boots.

Uchis – who recently released her third studio album Red Moon In Venus on March 3 – wore a white rhinestone-encrusted bustier top and the matching leather microskirt with fringe details.

The Colombian-American songwriter completed her look with a pair of over-the-knee white boots and her long, flowing locks in a high ponytail.