In a Twitter message before the formal ceremony, Harper said he was naming "four new, strong capable women" to the cabinet, the Canadian Broadcasting Corp. reported.
Harper's cabinet currently has 10 women.
Keeping their jobs are Jim Flaherty as finance minister and John Baird as foreign affairs minister. Also retaining their positions are Tony Clements as Treasury Board president and Ed Fast as trade minister.
Ministers new to the cabinet are Shelly Glover, Canadian heritage and official languages; Chris Alexander, citizenship and immigration; Kellie Leitch, labor and the status of women, and Kevin Sorenson, finance minister.
Also new are Pierre Poilievre, democratic reform; Candice Bergen, social development; Greg Rickford, science and technology; and Michelle Rempel, western economic diversification.