Captain Auston Matthews scored twice, while Zach Werenski, Brock Faber and Tage Thompson added goals to top Group C and automatically advance to the quarter-finals. But they missed out on the coveted top seeding on goal difference after Canada's 10-2 thrashing of France earlier on Sunday.
German goalie Maximilian Franzreb turned away 14 shots before defenceman Werenski ended the U.S. frustration, sending in a wrist shot with less than 10 seconds left before the first intermission off an assist from Matthews.
Fresh off the penalty kill, the U.S. doubled their lead as Matthews slipped a rebound through the legs of Franzreb on a power play early in the second period.
Defenceman Faber sent a slap shot in off an assist from each of the Tkachuk brothers, Brady and Matthew, putting the Americans up 3-0 heading into the second break.
The Americans never took their foot off the gas, as the towering Thompson rifled in a slap shot two minutes into the third and Matthews tapped in his second goal. The overwhelmingly pro-German crowd, which included retired tennis champion Boris Becker, got a bit of consolation when alternate captain Tim Stutzle got a score on the board.
Canada and the United States are joined in the quarter-finals by surprise Group B winners Slovakia and the next-best overall team, Finland. The remaining teams, including perennial contenders Sweden, compete in a single-elimination qualification playoff beginning on Tuesday.