The power of Majapahit reached its height in the mid-14th century under the leadership of King Hayam Wuruk and his prime minister, Gajah Mada. Some scholars have argued that the territories of Majapahit covered present-day Indonesia and part of Malaysia, but others maintain that its core territory was confined to eastern Java and Bali. Nonetheless, Majapahit became a significant power in the region, maintaining regular relations with Bengal, China, Champa, Cambodia, Annam (North Vietnam), and Siam (Thailand).

 Hayam Wuruk, also known as Rajasanagara, ruled Majapahit in AD 1350–1389. During his period, Majapahit attained its peak with the help of his prime minister, Gajah Mada. Under Gajah Mada's command (AD 1313–1364), Majapahit conquered more territories. In 1377, a few years after Gajah Mada's death, Majapahit sent a punitive naval attack against Palembang, contributing to the end of the Srivijayan kingdom. Gajah Mada's other renowned general was Adityawarman, known for his conquest in Minangkabau.

According to the book of Nagarakertagama pupuh (canto) XIII and XIV mentioned several states in Sumatra, Malay Peninsula, Borneo, Sulawesi, Nusa Tenggara islands, Maluku, New Guinea, and some parts of Philippines islands as under Majapahit realm of power. This source mentioned of Majapahit expansions has marked the greatest extent of Majapahit empire.

The Nagarakertagama, written in 1365 depict a sophisticated court with refined taste in art and literature, and a complex system of religious rituals. The poet describes Majapahit as the centre of a huge mandala extending from New Guinea and Maluku to Sumatra and Malay Peninsula. Local traditions in many parts of Indonesia retain accounts in more or less legendary from 14th century Majapahit's power. Majapahit's direct administration did not extend beyond east Java and Bali, but challenges to Majapahit's claim to overlordship in outer islands drew forceful responses.

The nature of the Majapahit empire and its extent is subject to debate. It may have had limited or entirely notional influence over some of the tributary states in included Sumatra, the Malay Peninsula, Kalimantan and eastern Indonesia over which of authority was claimed in the Nagarakertagama. Geographical and economic constraints suggest that rather than a regular centralised authority, the outer states were most likely to have been connected mainly by trade connections, which was probably a royal monopoly. It also claimed relationships with Champa, Cambodia, Siam, southern Burma, and Vietnam, and even sent missions to China.

Although the Majapahit rulers extended their power over other islands and destroyed neighboring kingdoms, their focus seems to have been on controlling and gaining a larger share of the commercial trade that passed through the archipelago. About the time Majapahit was founded, Muslim traders and proselytizers began entering the area.