In the early 1980s, Zeman felt that Hong Kong had no western restaurant that suited his needs, so in 1983 he opened California Restaurant in Lan Kwai Fong, a narrow street in Central. He bought the entire block in 1984 and thus launched his career as both an entertainment operator and property developer. Through Lan Kwai Fong Holdings Ltd, of which he is chairman, he drove the development of Lan Kwai Fong to be one of the most important bar and night life districts in Hong Kong.
In 2004, Zeman was invited by the then-Chief Executive of Hong Kong, Tung Chee-hwa, to become the chairman of Ocean Park. He managed to raise visitor numbers despite the opening of rival Hong Kong Disneyland, making the park more attractive and, remarkably, the park generated record profits.
In 2001, he was appointed a Justice of the Peace in Hong Kong, in 2004, he was awarded the Gold Bauhinia Star and in 2011 he was awarded the Grand Bauhinia Medal.