The Kingdom of Travancore (/ˈtrævəŋkɔːr/), also known as the Thiruvithamkoor Kingdom (Malayalam: [t̪iɾuʋid̪aːŋɡuːr]) and Travancore State, was a kingdom that lasted from c. 1729 until 1949. It was ruled by the Travancore royal family from Padmanabhapuram, and later Thiruvananthapuram. At its zenith, the kingdom covered most of the south of modern-day Kerala (Idukki, Kottayam, Alappuzha, Pathanamthitta, Kollam, and Thiruvananthapuram districts, major portions of Ernakulam district, Puthenchira village of Thrissur district) and the southernmost part of modern-day Tamil Nadu (Kanyakumari district and some parts of Tenkasi district) with the Thachudaya Kaimal's enclave of Irinjalakuda Koodalmanikyam temple in the neighbouring kingdom of Cochin. However Tangasseri area of Kollam city and Anchuthengu near Attingal in Thiruvananthapuram were parts of British India.

Malabar District of Madras Presidency was to the north, the Madurai and Tirunelveli districts of Pandya Nadu region in Madras Presidency to the east, the Indian Ocean to the south, and the Arabian Sea to the west.

Travancore was divided into five divisions: Padmanabhapuram, Thiruvananthapuram, Quilon, Kottayam, and Devikulam. Padmanabhapuram and Devikulam were predominantly Tamil-speaking regions with small Malayalam-speaking minorities. The divisions of Thiruvananthapuram, Kollam, and Kottayam were predominantly Malayalam-speaking regions with small Tamil-speaking minorities.

King Marthanda Varma inherited the small feudal state of Venad in 1723, and built it into Travancore. Marthanda Varma led the Travancorean forces during the Travancore-Dutch War of 1739–46, which culminated in the Battle of Colachel. The defeat of the Dutch by Travancore is considered the earliest example of an organised power from Asia overcoming European military technology and tactics. Marthanda Varma went on to conquer most of the smaller principalities of the native rulers.

The Travancore royal family signed a treaty with the British in 1788, thereby accepting British dominance. Later, in 1805, they revised the treaty, leading to a diminution of royal authority and the loss of political independence for Travancore. They had to give up their ruling rights over the common people in 1949 when Travancore were forced to merge with independent India.

The kingdom takes its name from Thiruvithamcode in the present-day Kanyakumari district of Tamil Nadu.

The region had many small independent kingdoms. Later, at the peak of the Chera-Chola-Pandya, this region became part of the Chera Kingdom (except for the Ay kingdom, which always remained independent). When the region was part of the Chera empire, it was still known as Thiruvazhumkode. It was contracted to Thiruvankode, and anglicised by the English to Travancore.

In the course of time, the Ay clan, part of the Chera empire, which ruled the Thiruvazhumkode area, became an independent kingdom, and the land was called Aayi Desam or Aayi Rajyam, meaning 'Aayi territory'. The Aayis controlled the land from the present-day Kollam district in the north, through Thiruvananthapuram district to Kanyakumari district in the south. There were two capitals, the major one at Kollam (Venad Swaroopam or Desinganadu) and a subsidiary one at Thrippapur (Thrippapur Swaroopam or Nanjinad). The kingdom was thus also called Venad. Kings of Venad had built residential palaces in Thiruvithamcode and Kalkulam. Thiruvithamcode became the capital of the Thrippapur Swaroopam, and the country was referred to as Thiruvithamcode by Europeans even after the capital had been moved in 1601 to Padmanabhapuram, near Kalkulam.