In 1988, she worked at the United States National Security Council.
The next year, she joined the Bureau of Western Hemisphere Affairs in the United States Department of State as Special Assistant to the Assistant Secretary of State for Western Hemisphere Affairs, becoming Executive Assistant to the Assistant Secretary in 1992.
She also served as Coordinator for Cuban Affairs.
From 1996 to 2000, she was director of the Office of Policy Planning and Coordination at the Bureau of Western Hemisphere Affairs, covering issues such as civil-military relations, human rights, foreign assistance, and counter-narcotics throughout the hemisphere.

From 2000 to 2002, she was Deputy Chief of Mission in the United States Embassy in Peru.
The American Foreign Service Association, which represents the interests of career diplomats, objected to her appointment because the post is normally reserved for a foreign service officer and she was a civil service employee.
Secretary of State Madeleine Albright overrode the recommendation of a State Department grievance board that recommended Jacobson be reassigned.
The U.S. ambassador to Peru, John Hamilton, had chosen Jacobson over several career diplomats.
He defended her selection in November 2000 saying: "She is the best manager I've come across in my 31 years in the Foreign Service".

Jacobson was Director of the State Department's Office of Mexican Affairs from December 2002 to June 2007.
 At that point, she became Deputy Assistant Secretary for Canada, Mexico and NAFTA issues in the Bureau.
She was Principal Deputy Assistant Secretary for Western Hemisphere Affairs from December 2010 until July 2011, with responsibility for regional political and economic issues, management and personnel, and regional security issues.

When Arturo Valenzuela left the Bureau of Western Hemisphere Affairs, she became Acting Assistant Secretary of State for Western Hemisphere Affairs.
U.S. President Barack Obama named her Assistant Secretary of State and she was sworn into office on March 30, 2012.

Jacobson led a U.S. delegation to Havana for historic talks with the government of Cuba in January 2015.
According to advance media reports, she was expected to press Cuba to drop travel restrictions on American diplomats and propose that Cuba and the United States establish an embassy in Washington and Havana respectively.

On November 10, 2015, the Senate Foreign Relations Committee approved Obama's nomination of Jacobson as the  U.S. ambassador to Mexico by a vote of 12–7.
Opposition to her appointment came primarily from the Republicans on the committee, notably presidential candidate Senator Marco Rubio.
He and six other Republican senators, along with Democratic Senator Robert Menendez, raised concerns about her position on normalisation of relations between Cuba and the U.S., human rights issues, and the failed extradition of Joaquín "El Chapo" Guzmán, who had escaped Mexico's highest security prison in July 2015.

The United States Senate approved her appointment to be U.S. Ambassador to Mexico on April 28, 2016.
She presented her credentials to Mexican President Enrique Peña Nieto on June 20, 2016.

On March 1, 2018, Jacobson filed her notice of resignation, effective May 5, 2018.

Jacobson is a member of the Inter-American Dialogue.
In 1988, she worked at the United States National Security Council. The next year, she joined the Bureau of Western Hemisphere Affairs in the United States Department of State as Special Assistant to the Assistant Secretary of State for Western Hemisphere Affairs, becoming Executive Assistant to the Assistant Secretary in 1992. She also served as Coordinator for Cuban Affairs. From 1996 to 2000, she was director of the Office of Policy Planning and Coordination at the Bureau of Western Hemisphere Affairs, covering issues such as civil-military relations, human rights, foreign assistance, and counter-narcotics throughout the hemisphere.
From 2000 to 2002, she was Deputy Chief of Mission in the United States Embassy in Peru. The American Foreign Service Association, which represents the interests of career diplomats, objected to her appointment because the post is normally reserved for a foreign service officer and she was a civil service employee. Secretary of State Madeleine Albright overrode the recommendation of a State Department grievance board that recommended Jacobson be reassigned. The U.S. ambassador to Peru, John Hamilton, had chosen Jacobson over several career diplomats. He defended her selection in November 2000 saying: "She is the best manager I've come across in my 31 years in the Foreign Service".
Jacobson was Director of the State Department's Office of Mexican Affairs from December 2002 to June 2007.  At that point, she became Deputy Assistant Secretary for Canada, Mexico and NAFTA issues in the Bureau. She was Principal Deputy Assistant Secretary for Western Hemisphere Affairs from December 2010 until July 2011, with responsibility for regional political and economic issues, management and personnel, and regional security issues.
When Arturo Valenzuela left the Bureau of Western Hemisphere Affairs, she became Acting Assistant Secretary of State for Western Hemisphere Affairs. U.S. President Barack Obama named her Assistant Secretary of State and she was sworn into office on March 30, 2012.
Jacobson led a U.S. delegation to Havana for historic talks with the government of Cuba in January 2015. According to advance media reports, she was expected to press Cuba to drop travel restrictions on American diplomats and propose that Cuba and the United States establish an embassy in Washington and Havana respectively.
On November 10, 2015, the Senate Foreign Relations Committee approved Obama's nomination of Jacobson as the  U.S. ambassador to Mexico by a vote of 12–7. Opposition to her appointment came primarily from the Republicans on the committee, notably presidential candidate Senator Marco Rubio. He and six other Republican senators, along with Democratic Senator Robert Menendez, raised concerns about her position on normalisation of relations between Cuba and the U.S., human rights issues, and the failed extradition of Joaquín "El Chapo" Guzmán, who had escaped Mexico's highest security prison in July 2015.
The United States Senate approved her appointment to be U.S. Ambassador to Mexico on April 28, 2016. She presented her credentials to Mexican President Enrique Peña Nieto on June 20, 2016.
On March 1, 2018, Jacobson filed her notice of resignation, effective May 5, 2018.
Jacobson is a member of the Inter-American Dialogue.
Roberta S. Jacobson