The complex, Nairobi's most upmarket shopping centre and a magnet for the east African nation's growing middle class and expatriates, was badly damaged in the assault by the Al-Qaeda-affiliated Shebab rebels and has undergone months of renovation.
Around 50 shoppers queued to be the first to pass through newly-installed metal detectors at the main entrance, after Nairobi governor Evans Kidero and Atul Shah, owner of the main regional supermarket chain Nakumatt, declared the mall back in business in a ribbon-cutting ceremony.
"I was coming to have a business lunch. The shooting was intense, and I went to hide in a flowerbed. I saw four terrorists... They shot at me and the ricochet from the wall went in my leg. They shot a security guard right in front of me," he recounted.
"They were young men. They were emotionless. They seemed to be enjoying what they were doing. Their faces I will never forget for the rest of my life."
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Since Westgate, the Shebab have continued to strike Kenya, with an even bigger attack in April when another four suicide attackers massacred 148 people in Kenya's northeastern Garissa University, most of them students.
The attacks have badly damaged Kenya's economy, with the country no longer so widely seen as a bastion of stability in the region. Tourism to Kenya, famed for its national parks, wildlife and Indian Ocean beaches, has also taken a major hit.
"Of course it was a trauma. For three months I had bad dreams," said Logilan, one of just a tiny number of siege survivors who have taken up their old jobs. "It's a nice place. You can meet different people. I feel secure.