The service delivered 34 containers of clothes and high street goods.
China Railway already runs services between China and other European cities, including Madrid and Hamburg.
The service passed through Kazakhstan, Russia, Belarus, Poland, Germany, Belgium and France before entering the UK via the Channel Tunnel.
In order to make the journey, a number of different locomotives and wagons were used as the railways of the former Soviet Union states have a larger rail gauge.
However, the rail firms say the service is still cheaper than air freight and faster than sending goods by sea.
The service is part of China’s One Belt, One Road programme – reviving the ancient Silk Road trading routes to the West.
In Yiwu, in eastern China, a bright orange locomotive pulling 44 containers laden with suitcases, clothes and an assortment of household goods set off on a 7,500-mile (12,000km) journey to western Europe.
Ten containers were taken off at the German cargo hub of Duisburg. The rest made up the first cargo train from China to arrive in London at Barking’s Eurohub freight terminal.
London is the 15th European city to find its way on to the ever-expanding map of destinations for China’s rail cargo. Last year, 1,702 freight trains made the voyage to Europe, more than double the 2015 figure.
Yiwu Timex Industrial Investments, which is running this service with China’s state-run railways, says prices are half that of air cargo and cut two weeks off the journey time by sea.
