By some estimates the second richest man in the country, he has been hit by restrictions along with dozens of other wealthy Russians.
Sanctions can include an asset freeze on funds and assets held in the European Union, as well as travel bans on individuals.
Mordashov made his fortune off a majority stake in Russian steel company, Severstal.
The action was taken following the Russian invasion of Ukraine last week.
The aim of the EU sanctions is to prevent Mordashov from disposing of his shares in Tui Group.
This is to prevent him “from realising any proceeds or profits from his investment in Tui,” a statement from the company said.
As a result of the war in Ukraine triggered by Russia, the European Union issued new sanctions on February 28th, which additionally include further representatives of the Russian economy.
Mordashov has been a shareholder in Tui Group for around 15 years and currently holds around one third of the share capital in the company.
“The European Union sanctions relate to Mordashov as a person, not to Tui Group, in which he is a shareholder,” a statement added.
“In this respect, these sanctions against the shareholder have no impact on the company in which he holds shares.”
Fritz Joussen, chief executive of Tui Group, had earlier sought to minimise the relationship between Tui Group and its largest shareholder.
Earlier this week he said: “We assume that any restrictions or sanctions against Mordashov will not have any lasting negative consequences for us as a company.