The Court of Appeal rule said racial identity should not be prioritised over the need for a loving family.
The rule came after a test case in which two black African boys, aged eight and 15, were allowed to be adopted by a white British couple despite their cultural differences.
Lady Justice Black said, according to the Mail Online: "The boys had a number of needs, not limited to important considerations related to nationality, culture and race, and there was no perfect way in which to satisfy all those needs.
"It is important to put the arguments about cultural heritage in context."
According to Lady Black, social workers usually only place a black child with white adoptive parents in "exceptional circumstances".
The boys' natural parents wanted to stop the adoption because they felt the white adoptive couple "could not meet [the boys'] cultural needs" or teach them about their Ghanian heritage.
However, according to the Mail, the children suffered emotional and physical harm when living with their biological parents. The judge also said the children will not be moved to adoptive parents who are better matched culturally.
The move comes after the Government urged social workers and judges not to regard race and culture as the paramount factors in matching children back in 2012.
Jeanne Kaniuk, MD of Adoption at Coram, a charity working with vulnerable children, said judges should seek to find a balance.
She told HuffPost UK Parents: "Decisions about matching children for adoption should seek to balance their need to find a stable, loving family with their need for that family to also nurture their cultural and racial identity.
"It is important to remember that children needing adoption have already suffered separation and disruption in their young lives.
"They will benefit most from a loving home where their identity and cultural background is valued and integrated into their daily life, even if it is not shared genetically with their adopters."
In an article commenting on adoption legislation on Coram's website, it states about transracial adoption: "Adopters must consider if their new child will be welcomed and integrated by their wider family to protect their child from compounded stigma.
"It is black and Asian children who wait longest or fail to be adopted. Mixed race children do not wait as long, but still wait longer than white children.
"We should encourage and welcome as many adopters as possible, and of greatest possible diversity."
Lady Black hopes the new ruling will help to break down the barriers preventing transracial adoptions, which has previously stopped children who could not return to their own parents from being placed with new families.