Philadelphia Union Logo

On May 11, 2009, the Philadelphia Union's name, crest, and colors were officially announced during a ceremony held at Philadelphia City Hall. "Union" alludes to the union of the Thirteen Colonies, of which Philadelphia was the first capital.The name was chosen following a fan poll held between January 19, 2009 and February 6, 2009; the other three options were AC Philadelphia, SC Philadelphia, and Philadelphia City.

The Union's colors are navy blue and gold, representing the primary colors of the Continental Army's uniforms during the American Revolutionary War. The team's crest is circular, symbolizing unity. Its thirteen gold stars represent the original Thirteen Colonies, while the shield's contour derives from the Philadelphia coat of arms. The rattlesnake pays homage to the "Join, or Die" political cartoon by Benjamin Franklin that was featured in the 1754 Pennsylvania Gazette, and is also reminiscent of the Gadsden flag, another Revolutionary icon. The light blue in the middle of the crest is a tribute to the Sons of Ben, and is further derived from the civic flag of Philadelphia. Coincidentally, the navy blue, gold, and light blue colors of the Union are also the predominant colors in the state flags of Pennsylvania, New Jersey, and Delaware. The team's secondary logo is a simplified version of the aforementioned design comprising the blue shield with the rattlesnake, augmented with a gold border and a ribbon bearing the team's official motto: "jungite aut perite", a Latin translation of the phrase "join or die", which was also used in the 1754 Benjamin Franklin political cartoon mentioned above.

In February 2013, the team unveiled a third uniform that commemorated Bethlehem Steel F.C., one of the most successful early American soccer clubs.The kit was primarily black with white trim, featuring a sublimated Union emblem, and a Bethlehem Steel F.C. jock tag.