Is it haram to buy fake football shirts?

Why fakes are a problem

A counterfeit shirt copies a club badge and a brand logo that someone else owns. Modern scholars and Islamic fiqh councils treat trademarks and intellectual property as real rights that can't be taken without permission. Using someone's name to make money they never agreed to is a form of taking wealth unjustly. The same reasoning covers pirated films and software. See Is it haram to download pirated movies or software?

Cooperating in wrongdoing

When you buy a fake, the seller is the one cheating most directly, but your money keeps that trade going. The Quran tells believers:

Counterfeit goods are often linked to underpaid factory labour and organised crime. The Prophet ﷺ also said, "Whoever cheats is not of me" (Sahih Muslim 102), which covers selling fakes as genuine.

The law matters too

In the UK, the EU and the USA, selling counterfeit goods is a crime, and importing them can lead to confiscation at customs. Muslims are expected to keep the lawful agreements of the country they live in. See Do I have to follow the laws of my country as a Muslim?

Where scholars differ

A minority of scholars don't see trademarks as property in the full fiqh sense and say the buyer of an obvious, cheap copy isn't sinning, as long as nobody is deceived. Most contemporary scholars disagree and treat it as a violation of others' rights. If you already own a fake shirt, you don't have to throw it away; just don't buy more, and never sell one as genuine.