Chiwenga, 61, played a pivotal role in recent developments that ended President Robert Mugabe's longtime rule.
His appointment is seen as a reward for the army's instrumental role in ending Mugabe's rule.
General Chiwenga took the oath of office in Harare on Thursday, pledging to be "faithful" to Zimbabwe, and to "obey, uphold and defend the constitution".
At the event held on the lawns of the president's official residence, Chiwenga, who is now one of the two country's vice presidents, vowed to "work as a team", and "deliver" whatever task given to him.
Chiwenga retired from the military last week, slightly over a month after the army temporarily took control of the country on November 15, culminating in Mugabe's resignation six days later and a takeover by his deputy.
The new president Emmerson Mnangagwa, dozens of government officials, military and police chiefs as well as traditional leaders, attended the event.
Chiwenga's rise to the country's second most powerful job has further consolidated the military's power in the politics of the southern African country.
Other top military officials were awarded ministerial posts earlier this month include ex-air force chief Marshal Perrance Shiri, who became the new agriculture minister, and a spokesman for the military, General Sibusiso Moyo, who was appointed as the new foreign minister.