Kinslow made his MLB debut with the Washington Nationals on June 4, 1886 as their starting catcher. He injured his finger in the third inning trying to catch a bad pitch thrown by Bob Barr, and had to leave the game. On June 15, he was again injured by a Barr pitch, and forced to leave the game with a dislocated finger. He played in three games for the Nationals in 1886, collecting two hits in eight at bats.