Fresh-faced Olivia Wilde looks radiant in effortlessly chic ensemble as she promotes 2015 Global Citizen Festival in NYC

She's known for her environmental advocacy, humanitarian work and philanthropy.

And Olivia Wilde was back at it on Wednesday, showing she wants to make a difference in the world by attending the 2015 Global Citizen Festival launch party at Milk Studios in New York City.

The 31-year-old actress proudly held up a promotional T-shirt while showing off her effortlessly chic city style as she made her way to the event.

Advocate: Olivia Wilde looked radiant as she attended the 2015 Global Citizen Festival launch party at Milk Studios in New York City on Wednesday

Advocate: Olivia Wilde looked radiant as she attended the 2015 Global Citizen Festival launch party at Milk Studios in New York City on Wednesday

'Mark your calendars. 9.26.15 #globalcitizen #NYC,' the beauty wrote on Instagram with a close-up of the blouse. 

The Tron star was spotted in a black and white printed T-shirt, long black blazer, and black flared jeans.

She spruced up her easy look with gold mirrored shoes, as her long bronde locks flowed down with a slight wave.

Retro: Olivia showed off her Seventies style by wearing a pair of black flared jeans 

Retro: Olivia showed off her Seventies style by wearing a pair of black flared jeans 

Trendy: The actress' locks are currently on trend with the hot 'bronde' hairdo 

Trendy: The actress' locks are currently on trend with the hot 'bronde' hairdo 

The mother-of-one wore a natural-looking palette of make-up to go with her look.

The Rush star appeared to have arrived alone, without her fiance Jason Sudeikis and their son Otis.

The couple, who began dating in November 2011, got engaged in January 2013 and have yet to set a date for their nuptials.

Proud: The mother-of-one happily held up her Globel Citizen Festival shirt

Proud: The mother-of-one happily held up her Globel Citizen Festival shirt

In April, Olivia launched an environmentally conscious line of clothes for H&M. The Conscious Exclusive collection is made of sustainable materials.

'I hope the collection empowers women around the world who love fashion but want to consume it in a more sustainable way. It gives them the chance to look their best, and also act responsibly. I also hope the rest of the fashion industry is watching. I think this is how all fashion should be. Great style that's naturally more sustainable,' she said of the line.

The star is also co-founder of Conscious Commerce, as site that ensures when you buy something the money actually goes to help the people who made it. 

More stars: Coldplay rocker Chris Martin was another famous face at Wednesday's event

More stars: Coldplay rocker Chris Martin was another famous face at Wednesday's event

The busy star recently wrapped production on the Christmas-themed comedy Love The Coopers with Amanda Seyfreid, Marisa Tomei, John Goodman and Diane Keaton.

She's also spent a lot of time promoting the Ebola documentary she produced, Body Team 12, which debuted at the Tribeca Film Festival in April.

Meanwhile, Chis Martin was another big name spotted at the launch party on Wednesday.

Happy camper: Chris was full of smiles as he spoke on stage

Happy camper: Chris was full of smiles as he spoke on stage

The Global Citizen Festival 2015 takes place on September 26th in New York City's Central Park.

'Global Citizen is a community of people like you. People who want to learn about and take action on the world’s biggest challenges—and use their power to get other people involved too,' according to the organisation's site.

'We bring you stories and actions that make a difference. That help fight extreme poverty and inequality around the world, and support approaches that will make life more sustainable for people and the planet.'

Mark your calendars. 9.26.15 #globalcitizen ������ #NYC

A photo posted by Olivia Wilde (@oliviawilde) on

 

The comments below have not been moderated.

The views expressed in the contents above are those of our users and do not necessarily reflect the views of MailOnline.

By posting your comment you agree to our house rules.

Who is this week's top commenter? Find out now