The pop star was honoured with the Trevor Hero Award at the ceremony held in The Hollywood Palladium in Los Angeles.
The 28-year-old star was recognised by the Trevor Project, which is the leading US national organisation providing crisis intervention and suicide prevention services to lesbian, gay, bisexual, transgender and questioning youth.
Katy looked angelic in the floor-length dress that included a sheer neckline and long sleeves to compliment its figure-hugging shape.
The Fireworks pop star added some extra glamour to her look thanks to some gold rings and a gold pendant.
Katy wore her hair in a girlish half up and half down braided fashion and her make-up look was heavy, with the star opting for accentuated eyebrows and layers of mascara to make her green eyes stand out.
Katy was chosen for the award as she encourages young people to believe in themselves and stand up for individuality. During the ceremony Abbe Land, executive director and CEO of the charity, explained more about why they picked the Fireworks singer to receive the accolade in 2012.
"We're honouring her because, really, she has done so much to empower youth. A couple years ago when, unfortunately, a lot of young suicides made the news… and there was a very visible presence of suicide, Katy stepped up and was out there in the community, speaking against it. Her support of marriage equality - and equality for everyone, really - is one of the many reasons we're supporting her as our hero this year," Abbe said. "Her song Firework is all about empowering youth to just be who they are, and that's what we try to do is make sure that when a young person reaches out to us. We are there to say, 'The way you are is perfect. Just be the way you are'."
Joining Katy in the best dressed stakes was Naya Rivera, who made a stunning entrance along with Rashida Jones and Anna Kendrick.
COMMENT RULES: Comments that are judged to be defamatory, abusive or in bad taste are not acceptable and contributors who consistently fall below certain criteria will be permanently blacklisted. The moderator will not enter into debate with individual contributors and the moderator’s decision is final. It is Belfast Telegraph policy to close comments on court cases, tribunals and active legal investigations. We may also close comments on articles which are being targeted for abuse. Problems with commenting? firstname.lastname@example.org