China United Network Communications Group Co., Ltd. (Chinese: 中国联合网络通信集团有限公司) or China Unicom (Chinese: 中国联通) is a Chinese state-owned telecommunications operator of China. China Unicom is the world's fourth-largest mobile service provider by subscriber base. On 7 January 2009, China Unicom was awarded WCDMA license to expand its business to 3G telecommunication.

The group had a special group structure to list its share. The group had a subsidiary China United Network Communications Limited (Chinese: 中国联合网络通信股份有限公司) which its A shares were traded in the Shanghai Stock Exchange (SSE: 600050), while an indirect subsidiary of the A share listed company, China Unicom (Hong Kong) Limited (Chinese: 中国联合网络通信（香港）股份有限公司) listed its shares in Hong Kong Stock Exchange as a red chip company (SEHK: 762) and in the New York Stock Exchange as American depository share (NYSE: CHU). The operating subsidiaries of the group were under China Unicom (Hong Kong). However, the group have some subsidiaries that involve in equity investment, such as "China Unicom Group Corporation (BVI) Limited", which were not injected to either listed companies.

China Unicom (known as Chinese: 中国联合通信有限公司 at that time) was founded as a state-owned enterprise on 18 June 1994 by the Ministry of Railways, the Ministry of Electronics Industry (zh) and the Ministry of Electric Power Industry (zh); the establishment was approved by the State Council in December 1993.

Started as a wireless paging and GSM mobile operator, it currently provides a wide range of services including nationwide GSM mobile network, long-distance, local calling, data communication, Internet services, and IP telephony in mainland China, and has operated a CDMA network in Macau since October 18, 2006. As of the end of April 2008, the company had 125 million GSM subscribers and 43 million CDMA subscribers. As of November 2008 the CDMA operations have been moved to China Telecommunications Corporation (China Telecom Group). UMTS (Universal Mobile Telecommunications System) has just launched in major cities across China on May 17, 2009.

In February 2000 a subsidiary "China Unicom (Hong Kong) Limited" was incorporated in Hong Kong and was listed on the Hong Kong Stock Exchange on June 22, 2000.They are an MVNO running on Three's 2G network. They are the only provider to sell SIM cards that provide native phone numbers on both sides of the border (charging slightly higher rates than local while in the mainland, but cheaper than roaming with another provider—in some cases even cheaper than a SIM from another Chinese province if being used in the Shenzhen–Guangzhou area).

The intermediate parent company "China Unicom (Hong Kong) Limited" was "China Unicom (BVI) Limited", As of 31 December 2001, the BVI company owned 77.47% shares of China Unicom (H.K.). In turn, China Unicom (H.K.) owned the operating subsidiaries of the group. In 2002, another intermediate parent company "China United Network Communications Limited" was established in Shanghai (headquartered in Beijing), to own 51% stake of "China Unicom (BVI) Limited" as well as listing the shares in the Shanghai Stock Exchange. As of 31 December 2002, state-owned China Unicom Group owned 74.6% shares of the A share company, in turn the A share company owned 73.84% of the BVI company. The BVI company owned 77.47% shares of the red chip company. To sum up, the Chinese Government via A share company, owned 42.67% stake of the operating subsidiaries, as well as additional 20.27% stake by the minority stake in the BVI company.

On June 2, 2008, China Unicom announced its intention to sell its CDMA business and assets to China Telecommunications Corporation (China Telecom Group) for a combined total of 110 billion RMB and to merge the remainder of the company, in a share swap valued at USD $56.3 billion (based on Unicom's stock last traded price) on June 2, 2008, with China Netcom. The CDMA business was officially moved to China Telecom in early November. It also continues the former China Netcom's and the former China Telecom's PHS mobile phone businesses.

In July 2009, China Unicom signed a $700 million deal with infrastructure vendor Ericsson to upgrade the company's GSM network.

In April 2012, China Unicom was a founding member in the formation of Cloud Computing Industry Alliance in Beijing. Other members of the alliance include Baidu, Tencent, and Alibaba.

In 2017 the A share listed company of the group introduced 10 strategic investors: state-controlled China Structural Reform Fund (zh), state-controlled listed company China Life Insurance, a private equity fund (Chinese: 腾讯信达有限合伙企业; literally: "Tencent–Cinda Limited Partnership") that was owned by China Cinda Asset Management and a company related to Tencent, a private equity fund partially owned by Baidu and Industrial Bank (Chinese: 百度鹏寰投资合伙企业), a private equity fund that related to JD.com (Chinese: 京东三弘企业管理中心; literally: "Jingdong Sanhong"), a public company Ali Venture Capital (Chinese: 阿里创业投资), a public company Suning Commerce Group and three minor private equity funds that was subscribed by companies such as Kuang-Chi and CRRC Group.

In the same year, the fund raised by the A share company was injected to the Hong Kong incorporated red chip company, via "China Unicom (BVI) Limited", for HK$13.24 per share (for a maximum of 6.64 billion share / HK$88 billion).

China Unicom Global Limited is a wholly owned subsidiary of China United Network Communication Group Company Limited. It was established on 24 June 2015, with its headquarter in Hong Kong. China Unicom Global is aimed to deliver direct and dedicate local support to customers outside Mainland China, including Asia Pacific, Americas, Europe, South Africa and the Middle East.

On 2 December 2016, China Unicom Global Limited launched the “CUniq” overseas mobile virtual network operator (“MVNO”) service in London, UK and unveiled the one-card-multiple-number service.

The "CUniq" one-card-multiple-number service provides a SIM card which works in Mainland China, Hong Kong (China) and the UK. The service may be extended to other areas.

In 2009, China Unicom (Hong Kong) agreed a US$1 billion cross-holding with Spain's Telefónica. In January 2011, the two partners agreed a further US$500 million tie-up in each other, which following completion in late 2011, Telefonica will hold a 9.7% shares in China Unicom (H.K.), while the red chip company will own 1.4% shares of the Spanish firm. The companies also agreed to deepen their cooperation in areas such as procurement, mobile service platforms, service to MNC's wholesale carriers, roaming, technology, among others, where both companies have been cooperating since the signature of their strategic alliance agreement.

In June 2012, China United Network Communications Group (China Unicom Group), the ultimate parent company of Hong Kong listed company "China Unicom (Hong Kong)", had agreed to buy back about 1.1 billion shares (approx. 4.6% of the share capital) of the red chip company from Telefonica for an approx. HK$11 billion. (HK$10.21 per share; by narrow band floating exchange rate approx. US$1.4 billion), via an unlisted subsidiary "China Unicom Group Corporation (BVI) Limited". Immediate after the deal, Telefonica still owned 5% of China Unicom (H.K.). In 2014 Telefónica sold a further 2.5% shares of "China Unicom (H.K.)" for HK$6.66 billion (HK$11.14 per share)

During year 2016, Telefónica sold a further 1.51% shares of "China Unicom (H.K.)" for HK$2.822 billion (HK$7.8 per share), As of 31 December 2016 Telefónica owned 1% shares of the red chip company (decreased from 2.51% year-to-yearly), as well as Telefónica's director César Alierta, still served as a director of "China Unicom (H.K.)".