Imperator finally left for her maiden voyage to New York on Tuesday, 10th June 1913, with Commodore Hans Ruser in overall command. Her maiden voyage had been delayed when she went aground soon after leaving the builders, then by a fire in a storeroom, followed by a boiler explosion. Finally, she sailed at 3.55pm, but immediately met a severe gale and heavy seas. When she arrived at Southampton on 11th June, she anchored off Ryde on the Isle of Wight, where she was given a full civic reception. She then sailed on to Cherbourg. She finally sailed for New York, with a total of 3,014 passengers aboard: 323 in First; 251 in Second; and 2,440 in Third and Steerage, plus 1,180 crew.
The crossing was dogged by bad weather and fog, although the passengers were determined to enjoy themselves. The maiden voyage took 6 days 5 hours and 12 minutes, covering 3,153 miles and averaging 21·13 knots. Arriving on 18th June, she passed Nantucket lightship at 12·50pm and anchored overnight at Quarantine. Once the harbour pilot had boarded she headed for her pier at Hoboken, New Jersey, escorted by a large flotilla of small welcoming boats.