The deal reached Tuesday reunites Hemsky with Jason Spezza after they were briefly teammates in Ottawa last season. Spezza came to Dallas in a trade before free agency opened.
The 30-year-old Hemsky spent his first 10 seasons with Edmonton before a midseason trade to the Senators in March. The Czech winger has 146 goals and 348 assists in 672 games.
The Stars also signed goalie Anders Lindback to a one-year contract. The 26-year-old appeared in 23 regular-season games and all four playoff games for Tampa Bay last season. The four-year veteran has a .904 save percentage and 2.74 goals-against average for his career.