Espinoza took part in postgraduate programs of Florida International University and Northwestern University.
From 1999 to 2000 she returned to her alma mater to study for a master's degree in economics.
In January 2005 Marisol Espinoza joined the Union for Peru party.
She was elected Congresswoman representing Piura in the 2006 legislative election.
Since July 2009 she has been speaker of the Nationalist bench in the Congress.
In the 2011 presidential election Espinoza was Ollanta Humala's running mate as candidate for First Vice President of Peru on the Peru Wins ticket.
On June 5 Humala was elected president, and Espinoza first vice president, with 51.5% of the votes, and took office on 28 July 2011.
Espinoza quit the Nationalist Party in September 2015 and left the Peru Wins benches in Congress a month later.
In the 2016 Congressional election she ran as an independent on the Alliance for Progress slate.