Kelly Rowland makes first appearance since secret wedding

Kelly Rowland has tied the knot.

The 33-year-old singer secretly married her long-term boyfriend Tim Witherspoon in Costa Rica on 9 May in a low-key ceremony — and made her first appearance as a married woman on Monday. Kelly glowed in a colourful ensemble as she graced the American Ballet Theatre Spring Gala in New York just a few days later and it's no wonder she was smiling so much.CLICK KELLY ROWLAND IMAGES FOR GALLERY

© Photo: Getty Images

Kelly Rowland looked radiant as she stepped out for her first appearance since tying the knot

No doubt aware of all the wedding speculation, Kelly, 33,

of her golden yellow sleeveless Lanvin dress,

.Nevertheless, numerous sources have confirmed that Kelly and Tim did say "I do" during their recent holiday in Costa Rica. "It was a

— only around 30 people," a source told

.

© Photo: Getty Images

Kelly Rowland married her fiancé Tim Witherspoon in a secret ceremony in Costa Rica over the weekend

Among those on hand to celebrate were

and her younger sister

, who flew out together for the nuptials following their

.Kelly's friend and former Destiny's Child bandmate

, showing her wearing what appeared to be

. She simply captioned the snapshot: "Good morning."

© Photo: Instagram

Former band mate Beyoncé was in attendance for the nuptials

Kelly

in December during an appearance on

."He put a ring on it," she said. "It's been a while. We've kept it very, very low - for years to be completely honest."The star also revealed that her long-term love popped the question over Skype. "It was so late — we were just staring at each other," she revealed.