The 34-year old Dane was the fans choice as the number one gloveman in North America's domestic league and will now take on European champions Chelsea at PPL Park on July 25.
Nielsen, who gains his second selection in the team following his 2010 inclusion, was thrilled to again be given the opportunity to play amongst Major League Soccer's best.
"It's a great honor and very exciting," he told bold.dk.
"This entire All-Star concept is something that they are very focused on over here. There have been so much publicity about it in recent months where there has been a vote about it, and I'm obviously delighted to have been chosen.
"It is something to be proud of and it is a reward for all the hard work that has been completed. And it also provides a spot on the team for the great exhibition match, which of course I am very pleased to play keeper."