Thomas the Tank Engine is to introduce a "homeless" Kenyan train to teach children about refugees.
A new series of the show will feature the Island of Sodor's first black female character, developed on the advice of the United Nations.
In the updated version, Nia, the Kenyan engine, will join other recently introduced international characters including Ashima from India and Shane from Australia.
Gender-balanced storylines were developed with the assistance of Tolulope Lewis-Tamoka, the UN Women's Africa Programme Adviser.
"We see that Nia doesn't have a home, so she has to stay in Sodor, where Thomas works side by side with her to get jobs done," she told the Radio Times.
"We're able to bring the idea of a refugee into the mind of a young person without calling them a refugee: someone who looks different to you might end up being your neighbour and very good friend."
The series will air in 33 languages across more than 110 countries. Lewis-Tamoka said in future the show could be an "awesome platform" for issues including violence against girls, equal pay and girls' education.
"The possibilities are endless," she said.
In 2013, the Labour MP Mary Creagh complained that Thomas was perpetuating "negative stereotypes" and said it needed more female engines in order to encourage girls to be train drivers.
The new show has been backed by the family of Rev Wilbert Awdry, who wrote the original stories to entertain his young son in the 1940s. The stories were turned into an animated series in 1984, narrated by Ringo Starr.
"We're always a bit possessive about Grandpuff's creation, but we understand the need to change things around a bit," said his daughter Clare Chambers.
"Both genders have loved it, but if the gender-balanced steam team encourages more girls to maintain an interest, that's great. What we care about most is that the series continues to reach people."