Pilibhit district (Hindi pronunciation: [piːliːbʱiːt̪]) is one of the 75 districts in the state of Uttar Pradesh in India, and Pilibhit city is the district headquarters. Pilibhit district is a part of Bareilly Division. In June 2014, Pilibhit Tiger Reserve was announced as the 46th tiger reserve of India.

Pilibhit district had its origins as a subdivision of Bareilly district in 1871, consisting of the parganas of Jahanabad, Pilibhit, and Puranpur, with a magistrate based in Pilibhit. It was then officially upgraded to a separate district in November 1879.

The early history of Pilibhit district is obscure. This area is traditionally considered to have formed part of the Panchala kingdom, whose capital was at Ahichchhatra, although there are no historical documents to confirm this. On the other hand, the many ruin sites in the district indicate that there was extensive settlement here, and that the forests which historically covered the area used to be smaller.

At Neoria Husainpur is a large area of ruins that became covered by dense forest. Mahof has a large ruined brick fort; Simaria Ghosu, not far away, has a mud fort, but it appears to have been built later than other ruins in the area. Several octagonal wells and a large masonry tank at Khaj appear to be the remains of a large town. Perhaps the most important ruins in the district are at Balai Khera, close to the town of Jahanabad. Nearby to the west is a mound called Parasua-kot, which is from the same time as Balai Khera.

There are many ruins in the forests of Puranpur tehsil, often marked by "unusually large bricks, often carved and chiselled in a most artistic manner." The ruins at Dhanaura have been partly washed away by the Chauka, but there are still several large ruin-covered mounds here, over a large area. Another site is at Suapara, a short distance north of Puranpur. The massive fortress at Shahgarh appears to have been occupied during a fairly late period, since coins of the Varmmas of Nepal have been found inside its walls. Further south is a large unnamed site where fragments of pottery, bricks, and glazed tiles have been found.

In the Bisalpur tehsil, there are extensive ruins at Marauri, on the Khanaut, and at Barkhera in the north there is a large mound that is traditionally said to mark the spot of a city built by the legendary Raja Vena.

The 10th-century Dewal inscription, which was found in 1829 at the village of Ilahabad, also known as Ilahabas Dewal, near Deoria. It is a Sanskrit inscription, dated to year 1049 of the Vikram Samvat (992 or 993 CE) and written in the so-called kutila script. The entire inscription is written as a 37-stanza poem, full of metaphors and mythological allusions, and documenting the construction of two temples to Shiva and Parvati by a local ruler and his wife. It was composed by a man named Nahila, son of Sivarudra, who was evidently well-versed in Sanskrit grammar and rhetoric.

The ruler mentioned in the inscription, Lalla of the Chhinda family, is described as a mandala-putra, or ruler of a province, and he was probably a feudatory of the kings of Kannauj. The text says that he "brought the river Katha to his capital", which according to H.R. Nevill probably refers to the digging of the canal now called the Katni. It also says that Lalla had the two temples built and endowed them with a quarter of the revenue from several villages. He gave the site the name "Devapalli", which is probably the same as "Dewal". The site of Garha Khera, a large 800-square-foot mound with two small tanks, was probably Lalla's capital; the Katni winds its way around this site. Atop a large mound on the south side of Ilahabad are the remains of a large temple, which is where the Dewal inscription was found.