 In the final year of his contract with the Penguins and approaching free agency, Niskanen finished the season establishing new career highs in goals (10) and assists (36) for 46 points.On July 1, 2014, Niskanen signed a seven-year, $40.25 million contract as a free agent with the Washington Capitals.In the 2017–18 season, Niskanen continued to play top-four pairing minutes with the Capitals, posting 7 goals and 29 points in 68 games.