Mortagne-au-Perche (French pronunciation: [mɔʁtaɲ o pɛʁʃ] ) is a commune in the Orne department in Normandy, northwestern France. It is classed as a Petites Cités de Caractère.

The arms of Mortagne-au-Perche are blazoned : Or, 3 fern fronds vert.

Historical population

Year	Pop.	±% p.a.
1968	4,322	—
1975	4,877	+1.74%
1982	4,851	−0.08%
1990	4,584	−0.71%
1999	4,513	−0.17%
2007	4,156	−1.02%
2012	4,059	−0.47%
2017	3,818	−1.22%
Source: INSEE

The Commune has seventeen buildings and areas listed as a Monument historique.

• Hôtel de Longueil a former 15th-century hotel, it was registered as a Monument historique in 1975.
• convent of the Poor Clares of Saint-François a former sixteenth-century convent, registered as a Monument historique in 1920.
• Saint-Nicolas hospital a former sixteenth-century hospital, registered as a Monument historique in 1997.
• Collegiate church of Toussaint a former thirteenth-century church served by a college of canons, registered as a Monument historique in 1972.
• Notre-Dame Church a fifteenth-century church, registered as a Monument historique in 1910.
• Saint-Germain-de-Loisé Church a fifteenth-century church, registered as a Monument historique in 1972.
• Mortagne Hippodrome the three wooden grandstands at this racecourse are the oldest preserved examples in France; they were registered as a Monument historique in 1996. The stands are used Each year on the first Sunday in September, for the Orne departmental competition for conformation and gait of Percheron horses.
• Hôtel a former eighteenth-century building, it was registered as a monument in 1975.
• Hôtel de Fontenay an eighteenth-century hotel, still in operation, it was registered as a monument in 1975.
• Hotel des Tailles an eighteenth-century hotel, still in operation, it was registered as a monument in 1971.
• House of Henry IV a sixteenth-century house, that Henry IV visited in 1599, it was registered as a monument in 1979.
• Dean Toussaint House a fifteenth-century house built for the dean of the collegiate church, it was registered as a monument in 1975.
• The house of the Counts of Perche a seventeenth-century stately house built on the site of where the counts of Perche resided in the 12th century, it was registered as a monument in 1975.
• Birthplace of Alain a nineteenth-century house where the philosopher Alain was born, it was registered as a monument in 1995.
• Turret house a fifteenth-century house, with a Turret, it was registered as a monument in 1975.
• Porte Saint-Denis a twelfth-century door, revealing a Cart arch that was the entrance to Fort Toussaint, it was registered as a monument in 1975.
• Statue of Neptune' located in the garden of the town hall, this statue was created in 1866 by Emmanuel Frémiet. It was registered as a monument in 2006.

• Geoffrey II, Count of Perche and Mortagne, grandfather of Queen Margaret of L'Aigle.
• Marie of Armagnac, duchess of Alençon, died there in 1473.
• Early Québécois settler Zacharie Cloutier (1590-1677).
• Jean-Pierre Poisson (1590-1650), an arquebusier who accompanied the explorer Champlain to Canada. Poisson returned to France, but some of his children emigrated to Quebec and left many descendants.
• City of Boucherville founder Pierre Boucher (1622-1717).
• Count Joseph de Puisaye (1755-1827), born in Mortagne-au-Perche, was the representative of the percheronne nobility in the Généraux States of Versailles of 1789. He rocks in the Counter-revolution after the arrest of the king and joined Chouannerie in Brittany. He was chosen by the Count d'Artois (future Charles X) to organize the English unloading of Quiberon in 1795 whose failure signs the end of his participation in the movement. He died exiled in Hammersmith, England.
• Ernest Granger (1844 -1914) French politician, was born here.
• Philosopher and antimilitarist Émile Chartier dit Alain (1868-1951), born in Mortagne-au-Perche.
• Fashion designer Chantal Thomass lives in Mortagne-au-Perche.
• Colonizer of Canada Pierre François de Rigaud, Marquis de Vaudreuil-Cavagnal.
• Journalist Jean Planchais (1922-2006), born in Mortagne-au-Perche.
• Michel Fleury - (1923 – 2002) historian, archivist and archaeologist, is buried here.
• Journalist and Swiss writer Alex Capus, born in Mortagne-au-Perche in 1961.
• Writer and music scholar Jean-Pierre Grivois, born in Mortagne-au-Perche.

Mortagne-au-Perche is twinned with:

• Wietmarschen, Germany

• Communes of the Orne department
• Perche