AOpen (Chinese: 建碁股份有限公司; pinyin: Jiànqí Gǔfèn Yǒuxiàn Gōngsī, stylized AOPEN) is a major electronics manufacturer from Taiwan that makes computers and parts for computers. AOpen used to be the Open System Business Unit of Acer Computer Inc. which designed, manufactured and sold computer components.

It was incorporated in December 1996 as a subsidiary of Acer Group with an initial public offering (IPO) at the Taiwan stock exchange in August 2002. It is also the first subsidiary which established the entrepreneurship paradigm in the pan-Acer Group. Currently, AOpen is a subsidiary of Wistron Group, a spin-off of the Acer Group.

They are perhaps most well known for their "Mobile on Desktop" (MoDT) solutions, which implements Intel's Pentium M platform on desktop motherboards. Because the Pentium 4 and other NetBurst CPUs proved less energy efficient than the Pentium M, in late 2004 and early 2005, many manufacturers introduced desktop motherboards for the mobile Pentium M, AOpen being one of the first.

AOpen specializes in ultra small form factor (uSFF) platform applications; digital signage; and product development and designs characterized by miniaturization, standardization and modularization.