Ahat, a former director at Premier League football club Everton FC, has lost his High Court appeal against being placed on the UK government's Russia sanctions list.
Mr Ismailov's lawyers argued the decision was 'outrageously unfair' during a hearing earlier this month.
The UK government's Russia sanctions list includes Russian nationals and entities with alleged ties to President Vladimir Putin.
The list is designed to target individuals and organisations accused of supporting the Russian government's actions in Ukraine.
The UK Foreign Office advises British nationals against all travel to Russia, citing the ongoing conflict in Ukraine.
The decision to impose sanctions on Mr Ismailov is likely to have significant implications for British nationals with connections to Russia.
The UK government has not commented on the specifics of Mr Ismailov's case, but the sanctions regime is part of the UK's broader efforts to support Ukraine and counter Russian aggression.