"Wow... I'm getting excited nervous!!!! Ahhhh!!!" she tweeted.
Back in September, the 25-year-old Vega, who was married once before, shared a photo of the yellow ring that Pena apparently built "from scratch."
This wedding comes a more than a year after Vega filed for divorce from "Spy Kids" producer Sean Covel in July of 2012. "We come to love not by finding a perfect person, but by learning to see an imperfect person perfectly," she tweeted at the time, quoting author Sam Keen. Vega and Covel were married for less than two years.
UPDATE: Pictures of Vega's dress have emerged. Big Time Rush's Challen Cates uploaded a photo hailing the event "the most fun wedding ever!" Friend Alec McPherson also uploaded a shot of "the cute couple #BTR #wedding #love #mexico."