United Microelectronics Corporation (UMC; Chinese: 聯華電子; pinyin: Liánhuá Diànzǐ) was founded as Taiwan's first semiconductor company in 1980 as a spin-off of the government-sponsored Industrial Technology Research Institute (ITRI).

Today, UMC is best known for its merchant foundry business, manufacturing integrated circuits wafers for fabless semiconductor companies. In this role, UMC is ranked behind competitors TSMC and GlobalFoundries. It has three 300 mm fabs, one in Taiwan and one in Singapore and one in China.

UMC is listed on the New York Stock Exchange under the ticker symbol of UMC, and on the Taiwan Stock Exchange as 2303. UMC has 10 manufacturing facilities worldwide, employing 10,500 people.

UMC was the first foundry to produce chips on 300 mm wafers, ship wafers using copper materials, to sell 65 nm IC's to customers, and to produce chips using 28 nm process technology. It was the first Taiwanese company to offer foundry services and the first semiconductor company to be listed on the Taiwan Stock Exchange in 1985.

The company was also known for producing semiconductor chips which were used in counterfeit Nintendo Entertainment System game cartridges. Nintendo of America filed a federal lawsuit against UMC for copyright infringement of the games. The case was settled, with both companies expressing satisfaction with the settlement.