Barnetta, 30, had been free agent this summer after his contract at Schalke expired, following a season in which he recorded three goals and five assists in 27 games for the Bundesliga side.
Per SI’s report, the Switzerland winger was attracting strong interest from the likes of Leicester, Augsburg and Real Betis but decided to make a permanent stateside switch after visiting Philadelphia last week and training with the Union to get a sense of the team.
Speaking to the club’s official website following the announcement of the 75-times capped midfielder’s signing, Union technical director Chris Albright said: “To add a player of Tranquillo’s quality will help us tremendously in what we’re trying to build.
“He’s a player with a real pedigree who chose to continue his career here in Philadelphia over other options. His experience and leadership will also be a great addition to our group as we push for the playoffs and make a run at The Open Cup."
With the Union sitting in ninth-place in the Eastern Conference after taking just 22 points from 22 games this season, Barnetta’s addition should prove a substantial coup considering he was said to be attracting interest from a Premier League outfit like Leicester.
Having started in the last 16 of the Champions League against Real Madrid back in March, it is no surprise that the Foxes would think he could still do a job in the English top-flight, but the three-time World Cup veteran will instead be showcasing his talent across the Atlantic.