The ruling on the front-page story from November comes amid heightened community tensions following the Brussels attacks this week claimed by the Islamic State group, which left 31 people dead.
The mass-selling daily claimed an exclusive poll revealed "1 in 5 Brit Muslims' sympathy for jihadis", and published a picture of Mohammed Emwazi, the British IS executioner known as Jihadi John, alongside the shock headline.
The story generated more than 3,000 complaints to the Independent Press Standards Organisation (IPSO), most of them challenging the coverage on the grounds of accuracy.
Complainants argued that the question did not specifically mention the Islamic State group, and could include those fighting against IS jihadists.
The Sun had denied that the wording of its poll was ambiguous, saying that previous questions in the telephone survey had made explicit reference to the IS group.
IPSO noted that the paper had provided various interpretations of the poll result inside but concluded that "the coverage was significantly misleading".
