After graduation, Riley became a manager, but in 1988, he turned professional when he joined the Albany Capitals of the American Soccer League. The Capitals did not renew his contract at the end of the season and Riley moved to the New Jersey Eagles for the 1989 and 1990 season. In 1990, the Eagles played in the American Professional Soccer League which had been formed by the merger of the American Soccer League and the Western Soccer League. Riley was 1989 All League and 1990 Second Team All League. In 1991, Riley moved down to Glen Cove of the New England Professional Soccer League. Glen Cove won the league championship as Riley was named MVP. In 1992, he again moved, this time to Hercules, again winning the NEPSL title. In 1993, he played for New York Atlas. In 1994, Riley returned to professional soccer with the expansion Long Island Rough Riders of the USISL. In 1995, Riley and his teammates won the league title. When he retired at the end of the 1997 season, Riley held the team's all-time career record for assists.
Coach
In 1986, Riley began his coaching career when CW Post hired him as an assistant. In 1990, Riley became head coach at CW Post, a position he held until 1997. Over his eight seasons as head coach, he compiled an 88–49–13 record. In 1997, Riley became the head coach of the Long Island Rough Riders, in addition to his duties as a player with the Rough Riders and head coach of CW Post. In 1999, Riley was named the USISL A-League Coach of the Year. In 2002, the Rough Riders moved down to the USL D3 Pro League, winning the league championship that season. His last season with the Rough Riders came in 2003. Over the years, Riley was involved with the Albertson Fury Soccer Club. In 2006, Riley became the head coach of the Long Island Fury of the Women's Premier Soccer League. The Fury was part of the Albertson Fury Soccer Club. Riley coached the Fury through the 2008 season. In September 2009, the Philadelphia Independence of Women's Professional Soccer hired Riley as the team's first coach. Riley was selected as the 2010 WPS Coach of the Year In 2011, he took the team to the championship where they fell in penalties to the Western New York Flash. In 2012, he became the head coach of the New York Fury. In 2013, Riley was named head coach of the Portland Thorns. After leading the team to a 16–17–11 record and one playoff appearance over two seasons, but finishing the 2015 season in sixth place, the Thorns declined to renew Riley's contract. On February 19, 2016, Riley was announced as the head coach of the WNY Flash of the National Women's Soccer League. On January 9, 2017, Paul Riley became the head coach of the NorthCarolina Courage franchise as the National Women's Soccer League announced that the WNY Flash franchise would be relocated to North Carolina.
