The Torchwood actor said that he and husband Scott Gill hope to give a second chance to troubled teenagers by raising them as their own.
"We haven't ruled out having children ourselves but it depends where my career takes us," he is quoted as saying in The Sun.
"We wouldn't want a baby. We'd look at adopting an older child or teenager who might have been in trouble. We would also look at adopting a gay child, thrown out of their home because of their sexuality.
"We have a lot to offer — chances and opportunities a young teen probably wouldn't normally get."
He added that until they are able to raise their own children, they will continue to look after their dogs Harris, Charlie and Captain Jack.
"For gay men and women without kids, dogs become our children. They may just be dogs to other people but they are more than that."
John Barrowman was recently named the UK's 'Top Celebrity Dog Owner' for 2012.
The actor has been cast in Grey's Anatomy creator Shonda Rhimes's new series Gilded Lilys.