President Sirleaf said she owed her own victories to women who came out in force to vote for her in 2005 and 2011.
According to UN Women, widespread illiteracy and discrimination based on sex also limit women's involvement in public life in the country.
The president has endorsed her vice-president for the top job but it is not clear if she will actively campaign for him.
Liberia's outgoing President Ellen Johnson Sirleaf says she will actively campaign for the handful female candidates contesting elections in October.
There is just one female presidential candidate among 20 contenders, as Sirleaf steps down as Africa's first female head of state after more than a decade in power.
"I will not be seeking re-election in the October 2017 polls. I will be on my feet everywhere in my own little way to campaign for women listed and certified by the National Elections Commission (NEC),” she said in a press statement issued Tuesday.
Sirleaf said she owed her own victories to women who came out in force to vote for her in 2005 and 2011 as she unified a nation emerging from the ashes of a civil war that ended in 2003.
She would be "reciprocating the Liberian women who stood under the sun and the rain — telling the Liberian people that we, the women of Liberia, this is our time," the statement said.
According to UN Women, Liberian women continue to suffer high rates of sexual violence, the legacy of a war in which rape was used as a weapon by rebel forces and government soldiers alike.
The agency also says widespread illiteracy and discrimination based on sex also limit women's involvement in public life in the country.
Beyond MacDella Cooper, the former fashion model turned humanitarian running for the presidency, only 15.9 percent of remaining candidates are women, according to NEC figures.
Joseph Boakai, Sirleaf's vice-president, is seeking the top job for the ruling Unity Party based on the record of peace and relative stability Liberia has experienced since Sirleaf was elected, and while he has received her endorsement, it is not clear if she will actively campaign on his behalf.