The Yongzheng Emperor (13 December 1678 – 8 October 1735), also known by his temple name Emperor Shizong of Qing, personal name Yinzhen, was the fourth emperor of the Qing dynasty, and the third Qing emperor to rule over China proper.

The fourth son of the Kangxi Emperor, Yongzheng ascended the throne following prolonged disputes over succession. A hard-working ruler, he aimed to create a more effective government, cracked down on corruption and reformed the personnel and financial administration. His reign also saw the formation of the Grand Council, an institution that had a major impact on the future of the dynasty. Militarily, Yongzheng continued his father's efforts to consolidate Qing's position in Outer Mongolia and Tibet through force.

The Yongzheng Emperor died in 1735 at the age of 56 and was succeeded by his fourth son, who assumed the throne as the Qianlong Emperor. Although his reign was much shorter than that of both his father and his son, the Yongzheng era achieved important reforms, but also considered by many to be authoritarian, with some describing him as a benevolent despot while others note that autocratic policies went too far.

Yinzhen was the eleventh recorded son of the Kangxi Emperor, and the fourth prince to survive into adulthood. His mother, historically known as Empress Xiaogongren, was originally a court attendant from the Manchu Uya clan. Around the time when Yinzhen was born, his mother was of low status and did not have the right to raise her own children. For most of his childhood, Yinzhen was raised by Noble Consort Tong, the daughter of Tong Guowei, the Kangxi Emperor's maternal uncle and an eminent official in the early part of the Kangxi Emperor's reign. She died when Yinzhen was just 9 years old. After she gave birth to more children, Yinzhen's mother was promoted to a pin and then to a fei, and became known as defei or "Virtuous Consort". The Kangxi Emperor did not raise his children only inside the palace. He also exposed his sons (including Yinzhen) to the outside world and gave them a rigorous education. Yinzhen accompanied his father on several inspection trips around the Beijing area, as well as one further south. He became the honorary leader of the Plain Red Banner during the Battle of Jao Modo between the Qing Empire and the Mongol Dzungar Khanate led by Galdan Khan. Yinzhen was made a beile in 1689 along with several brothers and promoted to junwang (second-rank prince) in 1698.

In 1709, the Kangxi Emperor stripped his second son Yinreng of his position as crown prince. Yinreng had been the crown prince for his whole life; his removal left the position of heir open to competition among the Emperor's remaining sons (the Kangxi Emperor had 24 sons who reached adulthood). In the same year, the Kangxi Emperor promoted Yinzhen from junwang to qinwang (first-rank prince) under the title "Prince Yong of the First Rank" (和硕雍亲王; 和碩雍親王; Héshuò Yōng Qīnwáng; Manchu: hošoi hūwaliyasun cin wang). Yinzhen maintained a low profile during the initial stages of the succession struggle. To appoint a new heir, the Kangxi Emperor decreed that officials in his imperial court would nominate a new crown prince. The Kangxi Emperor's eighth son, Yinsi, was the candidate preferred by the majority of the court as well as many of the Kangxi Emperor's other sons. The Kangxi Emperor, however, opted not to appoint Yinsi as his heir apparent largely due to apprehension that Yinsi's political clout at court was beginning to overshadow his own. Thereafter, Yinzhen sensed that his father was in favour of re-instating Yinreng as heir apparent, thus he supported Yinreng and earned the trust of his father.

Yinzhen (胤禛, 13 December 1678 – 8 October 1735) had the highest honor to orchestrate the imperial ceremonies and rituals during the reign of the Kangxi emperor, which illustrated that Yinzhen was well acquainted with the Confucianism traditions and customs. In the imperial court, Yinzhen was also deeply immersed in the state's affairs and heavily engaged in the political debates where he acquired diplomatic skills. As the Yongzheng Emperor (雍正, r. 1723–1735 CE) of Qing China, Yinzhen was indubitably a very diplomatically inclined ruler who created an institution of a "moral government" based on the Confucian principles. Yinzhen sought four distinctive qualities: loyalty—忠, fairness—公, sincerity—誠, and capability—能, from his subjects in order to run an effective court and to achieve stability. Li Wei (李衛, February 2, 1687 – December 3, 1738) was a recruit among the Qing officials to possess the desired virtues, and was regarded highly by Yongzheng.

A notable quote from Yinzhen captured during his reign as the Yongzheng Emperor in the 1720s expresses his imperial will:

小事小料理，不可因小而忽之，大事大振作，不可因難處而隱諱。朕意若果能如此實心奉行，以忠正一一字感化，不數年，賊亦人也。見文武大臣實心忠勇為國，屬員清正愛民，營伍整齊，士卒曉勇，而百姓不懷如是德，不畏如是威，仍去成群為匪者，朕想必無此理也。