The following is a list of transfers for the teams of the USL Pro league, the third level of the United States soccer pyramid, for the 2013 season. The transactions begin at the conclusion of the 2012 USL Pro season and end after the championship match of the 2013 season. The first signing of the season was former Aberdeen FC striker Darren Mackie who joined expansion side Phoenix FC. New players who are listed on a club's official roster but no official announcement was made appear at the end of the list.
The 2011 Lamar Hunt U.S. Open Cup was the 98th edition of the USSF's annual national soccer championship, running from June through early October. Seattle Sounders FC, who entered the competition as the two-time defending champions, successfully defended their title again. They became the third team in U.S. Open Cup history to win three straight U.S. Open Cups. As winner of the Open Cup, the Sounders earned a place in the 2012–13 CONCACAF Champions League Group stage. The farthest advancing USL Pro team was the Richmond Kickers.
The 2012 Charleston Battery season was the club's twentieth season of existence. It is the Battery's third consecutive year in the third tier of American soccer, playing in the USL Professional Division for their second season.
The 2013 Lamar Hunt U.S. Open Cup was the 100th edition of the oldest ongoing competition in American soccer. Qualification began in November 2012 in the fifth tier, although the United States Soccer Federation did not announce the format until March 5, 2013.
The 2012 Harrisburg City Islanders season was the club's ninth season of competitive soccer - its ninth season in the third division of American soccer and its second season in the USL Professional Division; the City Islanders being one of the original 10 founder-members.
The 2013 Richmond Kickers season was the soccer club's twenty-first season of existence. It was the Kickers' seventh-consecutive year in the third-tier of American soccer, playing in the USL Professional Division for their third season. The Kickers finished the season atop the USL Pro table, but lost in the playoff semifinals.
The 2013 Orlando City Soccer Club season was the club's third season of existence in Orlando. Orlando finished second in the overall regular-season table. They were declared 2013 USL Pro Champions after beating Charlotte Eagles 7–4 in front of 20,886 fans at the Fifth Third Bank Field at the Citrus Bowl.
The 2013 USL Pro season was the 27th season of third-division soccer in the United States, and is the third season of the United Soccer Leagues' (USL) PRO professional competition. The number of teams increased from eleven to thirteen with Phoenix FC and VSI Tampa Bay FC joining the league as expansion franchises.
The 2013 Phoenix FC season was the club's only season of existence, playing in the USL Professional Division.
The 2013 Charlotte Eagles Season will be the club's 21st year of professional soccer. It will be the team's third consecutive season in the USL Professional Division and the team will look to build on its 2012 Open Cup run from a year ago where they reached the quarterfinals.
The 2013 Pittsburgh Riverhounds season was the club's fourteenth season of existence. It was the Riverhounds' third season playing in the USL Professional Division. It was the first season the Riverhounds will play at Highmark Stadium, a newly built 3,500 capacity soccer specific stadium.
The 2013 VSI Tampa Bay FC season was the club's only season of existence. The club played in the USL Pro, the third tier of American soccer.
The 2013 season was the Harrisburg City Islanders's 10th season of competitive soccer - its tenth season in the third division of American soccer and its third season in USL Pro since the league was first created with the City Islanders as one of the original 10 founder-members.
The 2014 Pittsburgh Riverhounds season was the club's fifteenth season of existence. It is the Riverhounds' fourth season playing in the USL Professional Division. It was the second season the Riverhounds played at Highmark Stadium, a 3,500 capacity soccer specific stadium.
The 2014 USL Pro season was the fourth USL Pro season and the 28th season of third-division soccer in the United States.
The 2014 Orlando City SC season was the club's fourth season of existence in Orlando, and their final season playing in the lower divisions. A Major League Soccer expansion franchise with the same name began play in 2015. The team entered the season as the defending USL Pro champions, beating Charlotte Eagles in the Championship Game after finishing second in the regular season.
The 2014 Richmond Kickers season was the club's twenty-second season of existence, seventh-consecutive year in the third-tier of American soccer, and their third-consecutive season playing in USL Pro. For the second season, the Kickers reached the semifinals of the USL Pro playoffs, before losing to the Harrisburg City Islanders. The Kickers finished shy of defending their regular season title, finishing in fourth place in the league table. In the Open Cup, the Kickers were eliminated in the fourth round proper by Major League Soccer outfit, New England Revolution.
The 2014 Dayton Dutch Lions season was the club's fifth season of existence, and fourth consecutive season of playing in the third division of American soccer. The club played in USL Pro.
The 2015 Pittsburgh Riverhounds season was the club's sixteenth season of existence. It is the Riverhounds' fifth season playing in the United Soccer League, and the club's third season hosting matches at soccer-specific Highmark Stadium.
The Eastern Conference is one of two conferences in USL Championship soccer.