Over the course of his career, he held several cabinet positions, including as the Minister of French Civil Service in Jacques Chirac's second term as President of France.

[6] When Jean-François Copé resigned from his position as chairman of the UMP group in the National Assembly to become the party's secretary general in late 2010, Jacob succeeded him after defeating Jean Leonetti.

In response, the president of the Representative Council of Jewish Institutions of France (CRIF), Richard Prasquier, called Jacob's comments "a very great clumsiness".

[10] Under Jacob's leadership, the UMP (and later LR) parliamentary group asked for several votes of no-confidence in the government of Prime Minister Manuel Valls in 2014,[11] 2015[12] and 2016.

[18] Under Jacob's leadership, the Republicans' parliamentary group asked for a vote of no-confidence in the government of Prime Minister Édouard Philippe over the Benalla affair in 2018.

[24] Under Jacob's leadership, LR won more than half of the country's small towns in the 2020 French municipal elections; at the same time, however, the party lost in larger cities it had held for decades, including Marseille and Bordeaux.

[29] In 2014, Jacob criticized the Socialist majority for backing France's recognition of the State of Palestine as a move to "add fuel to the fire in a region that doesn't need that at all.

"[30] Ahead of Hollande's 2015 visit to meet President Vladimir Putin in Moscow, Jacob called on him to push for an end to the European Union sanctions on Russia over its activities in Ukraine.