Sheehan is one of only 12 women on the invite list for this prestigious event.
Amy's father Mark notified Snow Sports New Zealand of her late invitation to the games today.
Having just arrived in the States two weeks ago and after a long break from skiing, Sheehan's plan was to take it easy and focus on training. The invite came as a welcome surprise.
"Amy's decision to fly under the radar this season has allowed her to refocus on her passion for the sport and just have fun," said Mark.
"It could be that by taking the pressure off she was able to achieve her potential which in the end led to the invitation."
By chance, Sheehan was sharing the slopes with an X-Games selector who was so impressed with what she saw that she suggested Sheehan seriously consider competing in the Games.
Sheehan was invited to the practice day, which is virtually unheard of at an X Games, and by the end of the day she was officially added to the invite list.
"I am pretty stoked," said Sheehan.
"I have only been in the States for two weeks now and was looking forward to cheering on the boys (Lyndon, Joss and Byron)."
"As you can imagine I am rapt with the opportunity to represent New Zealand alongside them."
Amy's brother, Lyndon, remains on the alternate list for men's ski superpipe where, if he makes it, he'll join teammates Jossi and Byron Wells. Jossi will also compete in the men's ski slopestyle.
Shelly Gotlieb is the first snowboarder to represent New Zealand at an X Games. She will compete in women's snowboard slopestyle.
In all, New Zealand could field five athletes at the Games which is more than double the number ever before and a major achievement given the small number of athletes invited to attend.
Winter X Games 14 will be held January 28 through January 31, 2010 in Aspen, Colorado.
More than 200 of the best action sports athletes including past Olympians will compete in Skiing, Snowboard and Snowmobile. 51 Olympians participated in last year's Winter X Games.
All athletes receiving invitations to compete at Winter X Games 14 are chosen by a sport-specific selection committee. Criteria and timing of invitations varies by sport and discipline as it is based on the state and event schedules of that particular sport. The only exception is each gold medalist from Winter X Games 13 (2009) receives an automatic invitation to compete.
For a full list of invited athletes and more info, visit the ESPN X-Games site.