The key Scottish Government minister, who married Ali MacLennan in July last year, said “all being well” the couple were looking forward to a new addition to their family this summer.
Ms Forbes said she would be taking maternity leave from her role – and that she hoped she could show it is possible to combine a career in politics with a family.
Ms Forbes said in a statement: “My husband Ali and I are absolutely delighted to announce that we are expecting a baby later this year.
“All being well, we’re looking forward to welcoming a new member of the family in the summer.”
The announcement comes ahead of Thursday’s debate on the Scottish Budget for 2022/23, with Ms Forbes accepting she has a “very busy few months”.
"In the meantime, I have a very busy few months ahead including the final stage of the Budget this week and supporting people through the cost-of-living crisis,” she said.
“I will be taking maternity leave when the baby arrives, but I want to reassure constituents that my office will remain open, and my constituency team will continue to provide help and support, as normal, to the local residents of Skye, Lochaber and Badenoch.
“I have an even deeper admiration for the thousands of women across the country who balance both work and personal responsibilities. There might be particular challenges with being a politician in the public eye, whilst combating the side effects of pregnancy, but it is an experience which is familiar to countless women.
“Politics, like many workplaces, is often not renowned for being a supportive environment for parents. Hopefully I can play a small part in changing that and demonstrating that it is possible to have children and a career, with the right support in place.