After three seasons with the Senators organization, he was traded to the Washington Capitals for a ninth-round draft pick in the 2003 draft (a draft pick traded back to Washington just months later). He played much more ice time in his one full season with the Capitals, playing 80 games and scoring 6 goals and 12 points. He signed with the Florida Panthers in 2004, but spent the season with the San Antonio Rampage due to the NHL Lockout which cancelled the 2004–05 season. He was later loaned to the St. John's Maple Leafs for a run in the playoffs. When the lock-out was resolved, he finally played for the Panthers and in 73 games, he tied his NHL best of 12 points and scored 10 points in 41 games before being dealt to the Pittsburgh Penguins where he played just one game.
Kwiatkowski moved to the Swiss National League and first played for SC Bern from 2010–2012 before transferring to HC Fribourg-Gottéron for the 2012–13 season compiling 23 points in 46 games.
In his final professional season in 2015–16, Kwiatkowski opted to play in the Swedish Hockey League with Modo Hockey. Unable to help Modo avoid relegation, he produced 5 points in 42 games from the blueline.
On September 12, 2016, Kwiatkowski confirmed the end of his playing career in accepting an assistant coaching position with the Kalamazoo Wings of the ECHL.[1]