The Red Devils were comfortable under the Friday night lights at Old Trafford, as the Swedish star marked his home debut with a double, netting either side of half-time.
The 34-year-old now has three goals in his first two Premier League games, following on from his strike in Sunday’s Premier League opener at Bournemouth.
The former Paris Saint-Germain and Barcelona striker opened the scoring with a towering header before doubling his tally from the penalty spot early in the second half.
United had plenty of positives to take in Jose Mourinho’s first competitive home match in charge of the club. One of those was record purchase Paul Pogba, who played the full 90 minutes, less than two weeks after returning from pre-season and signing for his new club.
The Old Trafford crowd was excited to welcome their new world-record arrival in Pogba and he nearly scored inside half an hour as his effort deflected into Fraser Forster’s arms.
Swedish striker Ibrahimovic went close with an ambitious volley on the turn on 28 minutes before soon nodding United into a first-half lead.
After Rooney chased the ball into the corner, he was allowed too much space to take a touch and float in a cross. Ibrahimovic, marked by Portugal’s Euro 2016-winning defender Jose Fonte, rose highest to head the ball back across goal and past Forster.
Claude Puel’s Saints were nearly back on level terms four minutes into the second half, as Dusan Tadic finished off a good team move, but he was pulled up for the foul and his goal was ruled out. As the game opened up, United quickly attacked and Anthony Martial’s 20-yard shot was parried by England ‘keeper Forster.
Minutes later the home side were awarded the penalty when a former Saint, Luke Shaw, was fouled cheaply in the box by Jordie Clasie, who came on as a substitute in the first half to replace the injured Oriol Romeu.
Many were surprised when captain Rooney did not step up for the spot-kick, as the new man in town stepped up, sending Forster the wrong way and doubling his tally.
Pogba nearly marked his second debut with a goal as he headed a corner over from six yards, while Ibrahimovic had a couple of chances in a short space of time to add his third, his best chance a close-range header which he connected with poorly.
Shane Long sent a near-post header across goal and past the back stick in a rare scare for United, who looked comfortable for large parts of the Friday night meeting.
Ibrahimovic failed to net his hat-trick to cap on a fine first appearance in a red shirt at Old Trafford, but he certainly marked his arrival.