Peetoom is born in the province of North Brabant and grew up in the eastern part of the province of Groningen. She studied theology and ethics at the Vrije Universiteit in Amsterdam. Being a preacher of the Protestant Church in the Netherlands (PKN), she has been employed at the St. Nicholaschurch (Nicolaïkerk) in Utrecht since 2006.
From 1999 to 2005 she was a CDA member of the States-Provincial of Groningen. In 2010 she was vice-chair of the Frissen Commission, which investigated the CDA's huge loss in the Dutch general election, 2010. In April 2011 she was elected Party Chair of the Christian Democratic Appeal with over 60% of votes.