The 28-year-old has joined the Union from League Two club Leyton Orient after spending almost this entire career in the UK, apart from a brief stint in Thailand with Buriram United.
"Jay brings goal-scoring prowess to our team, in addition to a valuable veteran presence, as he has demonstrated with multiple clubs in England," said Philadelphia sporting director Earnie Stewart in a club release.
"He has played at the highest levels of club soccer, including in the [English] Premier League, and we are excited to add a forward of his quality to our squad."
The forward then ended up at Leyton in 2014 and scored 36 goals in 99 outings in all competitions for the O's, prior to this move to MLS with Philly.
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