Indravarman I was a king of Angkor who ruled from 877/78 to 889/890 his kingdom from Hariharālaya, where it was probably established by Jayavarman II. According to the inscriptions of the Práḥ Kô temple, consecrated on Monday, the 25th January 880 A.D.(Foundation stele K. 713 a three pairs of temple towers for three deceased kings and their queens were built by him as a kind of „memorial temple“, as can be seen by the inscriptions on the door frames of the towers: The central towers were dedicated to Jayavarman II under his posthumous name Parameśvara and his queen Dharaṇīndradevī (K. 320a), the northern ones for Rudravarman (consecrated as Rudreśvara) and Narendradevī (K. 318a), and the southern towers for Pṛthivīndravarman (consecrated as Pṛthivīndreśvara) and Pṛthi­vīndradevī (K. 315 a) and K. 713 b). According to the Lolei inscription K. 324 of Indravarman's successor Yaśovarman, dated 8 July 893 A.D., Rudravarman was the younger brother of the mother of Dharaṇīndradevī, the queen consort of Jayavarman II and mother of Jayavarman III whom Indravarman mentioned under his posthumous name Viṣṇuloka in his Bakong inscription K. 826 (stanza XXX), dated 881/82 A.D.

While Jayavarman II was credited for the founding of the Khmer Empire in around AD 800, Indravarman I was credited for the building program at Hariharālaya. He set the foundations for the future Angkorian kings to follow. The king's first act was to performed a public service for his subjects by building an irrigation network for the rice fields. The goal was usually achieved by constructing a large reservior to retain water during the Monsoon season and then released it during the dry season through a network of canals and channels. And in Hindu mythology the reservior also represents an ocean and the temple-mountain represents Mount Meru, the home of the gods. The king and his Brahman advisors performed many rituals throughout the year to reinforce this belief. For example, the ritual of rain-making performed before the rice planting season, etc. Immediately, after Indravarman I acceded, he declared in his Práḥ Kô inscription: "In five days from today I shall begin digging, etc." Dig he did with a reservoir of an immense size: the Indratāṭaka was the biggest reservoir ever built before his time being 3.8 km long by 800 meters wide. However, later rulers managed to out-build him and made his reservoir looked small. Now dry, it could have held about about 7.5 million cubic meters of water during the Monsoon season.

The king's second act was - as mentioned above - to build shrines and dedicated them to his god, ancestors, and parents, etc. At Hariharālaya, now called the Roluos group, Indravarman I built Práḥ Kô which he dedicated to his parents, wife, and the dynasty founder Jayavarman II.

The king's third act was to build a temple-mountain which he dedicated to a liṅga called after himself. Cœdès identified thirteen Angkorian kings after Indravarman built such shrines for these dual purposes (state and memorial shrine). The shrines were built with stepped pyramid surrounded by lakes. In the center of the capital of Hariharālaya, Indravarman I built Bakong surrounded by double walled moats. The Bakong was his state shrine, therefore, it also housed the official Śiva's liṅga. Although his shrines are bigger than his predecessors, they are modest compared to the later shrines.

Indravarman I died in 889/90 and was succeeded by his son Yaśovarman I.