In earlier times Palakkad was also known as Palakkattussery. Some etymologists trace the word "Palakkad" from the word Palai nilam, which means "dry lands". The commonly held belief, however, is that the name is a fusion of two Malayalam words, Pala, a tree (Alstonia scholaris) that is found abundantly in Palakkad, and Kadu, which means forest. Earlier days, palakkad along with most parts of Kerala were under the rule of the Chera kings (Perumals). With the decline of Chera dynasty, parts of this district were ruled by Palakkad Rajas who were believed to be a branch of Zamorins (Samudiri Rajavamsam) of Calicut who later declared independance.

Some parts were under Kollengode Rajas of Vengunad and the Valluvanad part of the district was ruled by Valluvakonathiris (who are considered to be descendants of a branch of Pallava dynasty who might have ruled parts of Kerala at an earlier date). For a brief period, some areas of the district near Chittur came under the attack of the nearby Kongu king when the local people resisted the Kongu invasion successfully.

Palakkad was a part of the Malabar District of Madras Presidency (during theBritish Raj, until 1947), then came under the princely state of Cochin and Madras state (from 1947 to 1956). It was made a separate district of Kerala when the state was formed in 1956.

To the east lies the Coimbatore District of Tamil Nadu. It is a predominantly rural district. Palakkad is the gateway to Kerala due to the presence of the Palakkad Gap, in the Western Ghats. The total area of the district is 4480 km² which is 11.5% of the state's area. Out of the total area of 4480 km², about 1360 km² of land is covered by forests. Most parts of the district fall in the midland region (elevation 75–250 m), except the Nelliampathy-Parambikulam area in the Chittur taluk in the south and Attappadi-Malampuzha area in the north, which are hilly and fall in the highland region (elevation >250 m). Some of the notable peaks in the district are Anginda (2325 m), Karimala (1998 m), Nellikotta or Padagiri (1585 m) and Karimala Gopuram (1439 m).

The climate is hot and humid for most part of the year. Palakkad is one of the hottest places in Kerala. There is sufficient rainfall. The district is blessed with many small and medium rivers, which are tributaries of the Bharathapuzha River. A number of dams have been built across these rivers, the largest being Malampuzha dam. The largest in volume capacity is the Parambikulam Dam