Archbishop Johan Bonny of Antwerp signalled his approval of gay unions in an interview with the De Morgen newspaper.
He said he favoured "formal approval" within the Church of same sex relationships.
The clergyman stopped short of saying Rome should accept gay marriage.
Archbishop Johan is a liberal in the Church and has already urged the Vatican to change its view on divorced Catholics.
"We need to look within the Church at a formal recognition of relationships which are also present in many bi couples - and homosexuals.
"Just as there are in society a variety of legal frameworks for couples, it should also be a variety of forms of recognition within the Church," he said.
He added that same sex couples should be able to receive a blessing in church.