Upon the creation of a new women's league in the United States, Women's Professional Soccer, many teams were interested in Smith's services.
She was chosen by the Boston Breakers second overall in the 2008 WPS International Draft, above Marta and under only Formiga.

Despite being drafted by Boston, she was still under contact with Arsenal.
However, Smith decided to leave Arsenal to join Boston Breakers on 18 February 2009, one of a number of English players to join the new Women's Professional Soccer League.

In the inaugural 2009 Women's Professional Soccer season, Smith appeared in 15 games (13 starts, 1170 total minutes) and scored six goals with two assists.
She was named to the WPS All-Star ballot, but was unavailable for the match due to England's participation at the European Championships.
In 2010 Smith started all her 21 appearances, leading the team with 11 goals and five assists.
She played in that season's All-Star game.
2011 saw Smith again afflicted by injury; she posted one goal and four assists in 10 appearances (nine starts, 850 minutes).
When the WPS went on hiatus ahead of the 2012 season, Smith was left "devastated" and without a club.
Upon the creation of a new women's league in the United States, Women's Professional Soccer, many teams were interested in Smith's services. She was chosen by the Boston Breakers second overall in the 2008 WPS International Draft, above Marta and under only Formiga.
Despite being drafted by Boston, she was still under contact with Arsenal. However, Smith decided to leave Arsenal to join Boston Breakers on 18 February 2009, one of a number of English players to join the new Women's Professional Soccer League.
In the inaugural 2009 Women's Professional Soccer season, Smith appeared in 15 games (13 starts, 1170 total minutes) and scored six goals with two assists. She was named to the WPS All-Star ballot, but was unavailable for the match due to England's participation at the European Championships. In 2010 Smith started all her 21 appearances, leading the team with 11 goals and five assists. She played in that season's All-Star game. 2011 saw Smith again afflicted by injury; she posted one goal and four assists in 10 appearances (nine starts, 850 minutes). When the WPS went on hiatus ahead of the 2012 season, Smith was left "devastated" and without a club.
Kelly Smith