The club launched legal action against the associated party transaction (APT) rules earlier this year on the grounds they were anti-competitive.
On Monday, City released a statement saying the tribunal had declared the APT rules "unlawful" and that the league had abused a dominant position under competition law.
They added: "The tribunal has determined both that the rules are structurally unfair and that the Premier League was specifically unfair in how it applied those rules to the club in practice."
The Premier League said the majority of City's challenges in the case were "rejected" but added: "The tribunal did, however, identify a small number of discrete elements of the rules which do not, in their current form, comply with competition and public law requirements.
"These elements can quickly and effectively be remedied by the League and clubs."^___^