Alibaba's stock has grown 87 percent since Zhang became CEO of the company in May 2015, and has a market value of around $420 billion, according to Fortune magazine.
The 46-year-old Shanghai native joined the company in 2007 as CFO of Taobao marketplace, Alibaba's online ecommerce platform, and has gradually risen up the ranks.
Contrast to founder Jack Ma, Zhang has kept a much lower profile.
"We don't know much about (Zhang) even though he's been CEO for a while, because he's by nature a very low-key person, low profile. He's happy to not be in the limelight," said Duncan Clark, author of "Alibaba: The House that Jack Built", according to a Reuters report.
Zhang has admitted as much himself. "Jack Ma is a guy with many ideas. He is very, very creative," Zhang said in an interview with the Financial Times last year. "But I'm the guy who always wants to put my foot on the ground."
One of Zhang's iconic achievements at Alibaba is the creation of the "Singles Day" shopping festival, a Black Friday-like online shopping spree held on Nov 11 every year.
Shoppers from home and abroad spent around 168.2 billion yuan ($245 billion) during last year's "Singles Day" festival, and it is now the world's largest 24-hour shopping festival, dwarfing similar shopping bonanzas round the world, including Black Friday in the US as well as Amazon Prime Day, which last year tallied $1 billion in sales, a SCMP report said.
But for Zhang, success has become a habit. The best team-building method is to move from one victory to another, he said at the closing of last year's "Singles Day" festival.
"Track customers' footprints online and recommend them their favorites doesn't mean a lot," said Zhang, "You recommend something that hits their hearts, though they've never bought or even seen it, that is real intelligence."
With "Singles Day" festival as a start, Zhang hopes to keep Alibaba evolving and creating something with disruptive innovation. "To redefine business as Apple Inc redefines a mobile phone," Zhang said so when describing his goal.
Zhang's academic background of finance and career experiences as CFO at Chinese gaming company Shanda and a senior manager at PwC's audit and business advisory division in Shanghai before joining Alibaba may explain his detail-oriented work style.
According to Ying Hong, former marketing director of Alibaba's e-commerce platform Tmall, the fighting power of the Tmall team has been formed based on Zhang's work style, which is to keep a perfect balance between strategy and details, said a report of iCEO.com.
"We are in the middle of a meeting, and the CEO would suddenly point at a chart slide and say 'there must be something wrong with this curve'," recalled one of Zhang's colleagues.
"He likes researching, and one needs to be familiar with every single details of a case to answer all his questions," Ying recalled. He bears more and more responsibilities at the company, and he wants to be sure that every detail behind a plan is real and solid, Ying added.
Zhang's continues victory can be attributed to the founder's continuous let go of power.
Alibaba invested $2.88 billion to obtain 36.16 percent of Sun Art Retail by acquiring shares from food retailer Ruentex in 2017. Huang Mingrui, chairman of RT-Mart, another potential competitor, is said to have never seen Jack Ma even as the negotiations were going on, as Zhang remained the face of Ma.
Alibaba teamed with its financial arm Ant Finance to fully acquire food delivery platform Ele.me early this year. The deal, with a transaction value of $9.5 billion, was solely sealed by Zhang.
"Group decision is a tradition in Alibaba," said a business insider who once worked at the company. Ma started to let subordinates make decisions five years ago. He spent over 800 hours on planes every year and doesn't inquire about cases worth less than 30 billion yuan, but the Alibaba Empire still runs well under the management of top executives like Zhang, the insider added.
And now it's time for Zhang to take over.
As Ma said in his open letter to the public on Monday, Zhang is "an outstanding business leader". His strategy and responsibility prove he is the correct choice, said Ma.