Rayong province (Thai: ระยอง, pronounced [rá.jɔ̄ːŋ]) is one of seventy-six provinces (changwat) within Thailand, and lies in eastern Thailand. The province is bordered by Chonburi to its west and north; Chanthaburi to its east; and the Gulf of Thailand to its south.^[5]

As of 2016^[update], per capita earnings were higher in Rayong province than in any other Thai province.^[6]

Rayong began to appear in 1570 in the reign of Maha Thammaracha, The Khmer Ruler has invaded Siam in the eastern coastal city but unable to seize the city.

Following the fall of Ayutthaya to the Burmese during the Burmese–Siamese War, the future king of the Thonburi kingdom, Taksin, arrived in Rayong. In Rayong, Taksin built a new navy before going on to Chanthaburi to assemble forces to fight the Burmese. Taksin then passed back through Rayong during the reunification of Siam as the Thonburi kingdom. The oldest temple in Rayong, Wat Pa Pradu, is dedicated to Taksin where locals worship his spirit.^[7]

In 1906, Rayong was merged to Monthon Chanthaburi. In 1908, Klaeng district was merged to Rayong.

In the reign of King Rama VI, changed the name of "Rayong City" to "Rayong province" in 1916 but it still part of Monthon Chanthaburi. Later in 1931, Monthon Chanthaburi was dissolved and Rayong was merged to Monthon Prachinburi.

Although the north is hilly, the province consists mostly of low coastal plains. The total forest area is 292 km² (113 sq mi) or 8 percent of provincial area.^[8] Off the shoreline of Mueang Rayong District is Khao Laem Ya–Mu Ko Samet National Park, consisting of several islands.

The seal of the province shows the island Ko Samet. The provincial tree is the Alexandrian laurel (Calophyllum inophyllum). Neolissochilus soroides is a provincial fish.

Rayong is one of the three Thai provinces, together with Chonburi and Chachoengsao, at the center of the nation's Eastern Economic Corridor. The three provinces are to become Thailand's hub for manufacturing, research, and services tightly coupled with its ASEAN neighbors and the world logistically.^[10] The project is the centerpiece of the government's "Thailand 4.0" economic initiative.^[11][12]

Rayong's main hospital is Rayong Hospital, operated by the Ministry of Public Health.

Since 2003, United Nations Development Programme (UNDP) in Thailand has tracked progress on human development at sub-national level using the Human achievement index (HAI), a composite index covering all the eight key areas of human development. National Economic and Social Development Board (NESDB) has taken over this task since 2017.^[3]

• Petchara Chaowarat (born 1943), Actress
• Dhawee Umponmaha (born 1959), Muay Thai kickboxer and 1984 Olympics silver medalist (Light welterweight)
• Amphol Lumpoon (born 1963), Rocker and actor
• Kittisak Rawangpa (born 1975), Footballer
• Jirayu La-ongmanee (born 1995), Actor
• Stamp Fairtex (born 1997), Muay Thai kickboxer and mixed martial artist (ONE Championship)

• The cape of Khao Laem Ya in the morning, Khao Laem Ya – Mu Ko Samet National Park
• Khao Laem Ya – Mu Ko Samet National Park
• Khao Laem Ya – Mu Ko Samet National Park
• Khao Laem Ya – Mu Ko Samet National Park
• Khao Laem Ya – Mu Ko Samet National Park
• Khao Laem Ya – Mu Ko Samet National Park
• Khao Chamao (Khlong Nam Sai) Waterfall, Khao Chamao–Khao Wong National Park