The 23-year-old reached the summit before dawn along with his sherpas and another expedition member after leaving from Camp 3.
With the Cho Oyu summit, Mr Arjun has climbed five of the 14 highest mountains in the world that tower over 8000 mt and holds world records as the youngest summiteer on Mount Lhotse, Mount Manaslu and Mount Makalu.
"I felt overwhelmed and humbled standing on top of this big and challenging mountain. I summited at 6.20 IST under very cold conditions along with my two Sherpas Pasang Norbu Sherpa and Lakhpa Sherpa," said the mountaineer via a WhatsApp call.
Mr Arjun, a Noida resident, unfurled the Indian tri-colour on the little bump that marks the Cho Oyu summit after a 7 hour, all-night climb through rocky steps, mixed snow and a long traverse to the top. After taking a 360 view from the summit, Mr Arjun and the two Sherpa's have begun their descent to Camp 1.
"The cold has gripped us further due to lack of sunlight and we need to head down and get inside our tent and drink warm fluids," he said before starting the long journey back to camp 1, via the standard North West ridge route, at 6400 mt.
The Mount Cho Oyu 2016 expedition was a personal challenge for the young mountaineer because he had suffered a paralytic attack during his first attempt in 2011 and he had to work his way back to physical fitness to climb again.
His aim is to be the youngest mountaineer/adventurer to complete the True Explorers Grand Slam (climbing the 14 highest mountains) as well as complete the Grand Slam (7 highest summits in 7 continents and walking to the North and South Poles).