Joel Ward was the hero for the Capitals, slamming home a rebound at the 2:57 mark of overtime.
It was the seventh-straight game in the series to be decided by a single goal—a first for the NHL.
The Capitals struck first when Matt Hendricks deflected a John Carlson shot into the Bruins goal at 14:27 of the first period.
Late in the second period, Johnny Boychuk took a slap shot that squeezed through Braden Holtby and came to rest in the crease. Tyler Seguin made a diving stab at the puck, poking it home to even the score.
The game remained tied late in the third when a holding call on Jason Chimera put the Bruins on the power play. However, it proved to be insignificant as the Capitals killed off the penalty to force overtime.
Joel Ward’s overtime winner came on a bad line change by the Bruins that led to a two on one for the Capitals. Thomas made the first save on Mike Knuble, but was unable to get to the rebound as Ward ended the series.
While offensive stars Alex Ovechkin, Nicklas Backstrom and Alexander Semin played well—combining for 12 points in the series—goaltender Braden Holtby was the key to the Capitals' success.
The 22-year-old Holtby made 31 stops in Game 7, adding to his already impressive series stats. He finished with a 2.00 goals-against average and a .940 save percentage. Remarkable numbers for a goaltender with 21 games of prior NHL experience.
With their speed, skill and spectacular goaltending, the Washington Capitals may be poised for their longest playoff run since 1998 when they lost in the Stanley Cup final to the Detroit Red Wings.