Back to 9 BC in the Zhou Dynasty, ancient Chinese who lived in coastal area of South China or the south of the Five Ridges(Lingnan) were known as Yue(越) people.

They built relationship with the state of Chu in the middle reaches of Yangtze River, and built Chuting(楚庭), which was the earliest name of Guangzhou city. Today a memorial gateway lying on the Yuexiu Hill still reads four Chinese characters“古之楚庭”(Ancient Chuting).

In 214 BC, the First Emperor of Qin united China and established in Lingnan three new commanderies (jun郡) —Guilin, Xiangjun and Nanhai. Ren Xiao, the first governor of Nanhai, built a city on Pan and Yu hills. Hence the city got its name—Panyu (present-day Guangzhou), situated on the highlands between today's Zhongshan Si Lu and Cangbian Lu. With Panyu as its administrative center, Nanhai administered most part of present-day Guangdong province.

Then Zhao Tuo, general of Qin, established the Nanyue Kingdom, with Panyu as the capital city. The city was expanded into a large city with a circumference of ten miles during this historical period and thrived in terms of culture and foreign trade as the sea routes developed.

In the late Eastern Han Dynasty, China was divided into 13 prefectures (zhou州). Panyu was included in Jiaozhou which had jurisdiction over today's Guangdong province, Guangxi Zhuang Autonomous Region (GZAR) and the north-central Vietnam.

In 217, Jiaozhou's administrative center was relocated from Longbian (present-day Bac Ninh Province of Vietnam) to Panyu by Bu Zhi, then prefectural governor of Jiaozhou, as he considered Panyu enjoyed greater advantages in geographical location, agriculture and commerce. Under Bu Zhi's effective governance, Panyu city was further expanded and developed and local people hailed it as Bu Zhi city.

By the Three Kingdoms Period ( 220-280) , Lingnan was under control of the state of Wu(229 - 280) and was separated into two prefectures——Jiaozhou and Guangzhou. The name of Guangzhou has ascended on the history stage since then. With Panyu as its administrative center, Guangzhou administered nowadays Guangdong province and most part of GZAR.

During Sui and Tang dynasties, Guangzhou was known as Guangzhou Zongguan Fu( the general prefecture总管府) and Guangzhou Dudu Fu (the institution of the Area Command都督府) respectively. In particular, Guangzhou Dudu Fu, with a total area of 42,000 square kilometers, was the administrative center of Lingnan Dao (道circuit or province). During this period, Guangzhou not only expanded its urban area, but also became the largest port in China due to its prosperous maritime trade.

In 917, Liu Yan established the Southern Han Dynasty in Lingnan, with Guangzhou as its capital city. The emperor renamed the city Xingwang Fu, and greatly promoted the city’s infrastructure construction, being a new chapter in the history of Guangzhou. Then the name of Xingwang Fu was abandoned as the Southern Han Dynasty perished in 971.

Later the Song Dynasty enforced the circuit (lu路)system as the country's a territorial administrative unit , dividing Lingnan into two areas, namely Guangnan Xi Lu and Guangnan Dong Lu. Guangnan Dong Lu was basically today's Guangdong, and Guangzhou was once again announced as the administrative center. Guangzhou kept booming in this period as rulers of Song implemented a series of positive policies to promote productivity.
The Yuan Dynasty "invented" the modern province (xingsheng行省, later sheng省), and the Ming empire inherited it. The names, sizes and locations of the Ming provinces were largely identical to those of modern China. The provinces were divided into supreme prefectures (fu府) and secondary prefectures (zhou州). Therefore, the name of Guangzhou Fu was being used from Ming to Qing Dynasty.
But what well-worth mentioning here is that Guangzhou served as the only port for foreign trade in China during Qing period, but it was widely known as Canton among westerners.

According to the book Canton Guide, written by John Glasgow Kerr in 1889, the City of Canton was situated on Pearl River, 90 miles from Hong Kong. It was the Capital of Kwong-tung Province(广东省), and contained about 1,000,000 inhabitants. On maps published in foreign countries or in English versions published in China, Guangzhou is often accompanied by a parenthesis that says 'Canton'.
How exactly the name of Canton came wasn't recorded clearly, but it does have a marked impact on the history of Guangzhou. Even today, the word of Canton is still used frequently, such as in Canton Fair, Canton Festival and Canton Tower.

Since the beginning of the 20th century, people who work with the Chinese language have designed several systems of phonetic symbols to deal with the fact that Chinese characters do not fully represent their pronunciations. The "Chinese Phonetic System", abbreviated "pin yin", was first published in 1958.
This system has already been adopted by the United Nations and many other international organizations for spelling the Chinese language, and writing personal and place names. Thus, Guangzhou is widely used both inside and outside of China.