Her success came after she helped Hong Kong finish third at the World Junior Team Championships, in May in Poland, and then won the Asian Junior Championships in Jordan, the following month.
Days after her top ranking was announced in August, she retained her Hong Kong Junior Open title in what was her final match as a junior.
Ho's junior reign officially ended yesterday, when she celebrated her 19thbirthday - and joined the ranks of senior players.
"I was really surprised to be told I'd become the world number-one," says Ho, who is in her second year of studies for a higher diploma in hotel management at Hong Kong Polytechnic University.
"It was really only a calculation and didn't indicate I was the best junior player at the time. But I'm glad that I had a good, steady series of performances this summer to gain more points than other players. That's still a big achievement."
Ho began to play mini-squash at primary school, aged eight or nine, and first represented Hong Kong, aged 14, at the 2009 World Junior Team Championships.
"Becoming a senior means I'll face much stronger players," she says. "I can stop wearing the safety goggles you wear as a junior, but I'll keep using them for a while: it feels safer playing when they're on.
"It does mean that when I play my first few international tournaments, my rivals will know I'm new to the senior world," Ho laughs.
Ho normally practises at the Hong Kong Sports Institute for two hours, five to six times a week. But after her exams last summer, she was training 10times a week, including running and gym work.
"I found the training very hard, especially the fitness exercises and running," Ho says. "But I knew it was the end of my time as a junior, so I wanted to get some good results.
Early this year, Ho's coach, former Asian Games champion Rebecca Chiu Wing-yin, handed a piece of paper to Ho and the other juniors training with her. Ho says: "We had to list our strengths and weaknesses as players, and our specific targets in tournaments."
Ho met all her targets.
"I said I wanted to win the Asian Junior Individual Championships and Hong Kong Junior Open, and finish in the top three at the World Junior Team Championships."
She also won an extra title, June's Penang Junior Open, in Malaysia.
All this success, as well as reaching the last 16 in the World Junior Individual Championships, helped her amass 90 ranking points to top the quarterly junior rankings, released in August.
As a senior, she is now 120th in world, in this month's latest rankings, thanks to some good results at tournaments over the past 12 months, including three senior international events in Hong Kong and Macau.
She says becoming the world number one is a dream too far right now. "One day, when I become a full-time professional and the team sends me to more senior international tournaments, I'd like to get into the top 50," she says.
"To plan to become the top-ranked senior is really unrealistic at the moment. But I really want to copy the success of reigning world number-one Nicol David, from Malaysia. There are always challengers, but David has retained her top ranking for the past seven years or so. That's spectacular."
Ho is trying to decide whether to become a full-time professional now, or continue part-time for two years and finish her degree.
"If squash had been picked as a new Olympic sport at the 2020 Tokyo Games it would have been an easy decision. But now there won't be any chance for me to play at the Olympics before I turn 30.
"I need to discuss things with my coach, Tony Choi, to work out what to do: there's next year's Asian Games to focus on, too.
"But whatever I decide, I won't stop playing. I've been with Hong Kong's team since Form Two: it's not time to say goodbye to squash."
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