Souness snubbed many people’s pick, Chelsea’s tireless midfielder N’Golo Kante, in favour of the 35-year-old forward.
Ibrahimovic, who signed for United in the summer on a free transfer, has been a revelation up front, finding the back of the net 16 times in the Premier League.
The Red Devils have relied heavily on the Swede’s goals all season, having scored the least of any top seven team.
And Souness believes the striker to be a worthy winner of the award.
“I have just voted for Ibrahimovic as my Player of the Year because he has been that good,” Souness told Independent.ie.
“However, with my Liverpool hat on, how concerning must it be to United that their best player by a considerable distance is a 35-year-old who might not be there next year.”
Souness, who both played for and managed Liverpool, argued that the Red Devils have been lacking a “killer instinct” in front of goal this season.
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And things would be a lot more difficult for them without Ibrahimovic’s influence.
He also suggested that Michael Carrick may just be United’s next best player, which is a worry for supporters given that he is the same age as the Swede.