On 23 August 2013, as a free agent following his buy-out, Grabovski signed a one-year, $3 million contract with the Washington Capitals. In his first regular season game with the Capitals on 1 October 2013, Grabovski scored a hat-trick in a 6–4 loss to the Chicago Blackhawks. Grabovski completed the 2013–14 season with a respectable 35 points in 58 games as the Capitals failed to reach the Stanley Cup playoffs for the first time in seven seasons.
On 9 February 2013, Grabovski was accused of biting Max Pacioretty of the Montreal Canadiens during a scrum along the boards. The NHL conducted a telephone hearing with the players involved, but could not determine conclusively if Grabovski had indeed bitten Pacioretty. However, on 20 May 2013, more than three months later, Grabovski admitted that he did bite Pacioretty, stating in an interview, "He was choking me and I bit him. Don't stick your hands where you shouldn't."
On 3 July 2013, after learning that his contract was being bought-out by the Toronto Maple Leafs, Grabovski was very critical of Toronto's head coach at the time, Randy Carlyle, in an expletive-filled interview with TSN. "I play in the fucking Russian KHL, I make lots of fucking points and what's going to happen? He make me fucking play on the fourth line and he put me in the playoffs on the fourth line and third line again," said Grabovski. "I don't feel any support from this fucking idiot."