$723m (£551m) has been approved by the Word Bank for Ukraine.
The money approved as loans and grants is to support the country as it battles Russian invaders.
The bank said it is continuing to work on another $3bn package of support in the coming months for the country if the war continues to escalate.
The bank also promised extra help for neighbouring countries that are taking in more than 1.7m refugees, which are mostly women, children and the elderly.
The bank said the funds would help Ukraine's government provide critical services, including wages for hospital workers, pensions for the elderly and social programmes for the vulnerable.
The bank says the financial package for Ukraine includes a $100m pledge from the UK.
"The World Bank Group is taking quick action to support Ukraine and its people in the face of the violence and extreme disruption caused by the Russian invasion," the bank's president David Malpass said in a statement.
The package includes a $350m loan, plus $139m through guarantees from the Netherlands and Sweden.
It is also made up of $134m in grants from Britain, Denmark, Latvia, Lithuania and Iceland, as well as $100m of financing from Japan
