Tencent built up its stake over the course of around a month, before hitting the five per cent disclosure threshold on 30 April.
The buy-now-pay-later model has seen huge growth in recent years, propelling Afterpay to a market capitalisation of over A$8 billion on the ASX.
The firm has been building up its presence in the US and also operates in the UK under the Clearpay brand.
Last month, Tencent rival Ant Financial invested an undisclosed amount in Swedish buy-now-pay-later brand Klarna.
In a statement, Afterpay co-founders Anthony Eisen and Nick Molnar says the investment offers the “potential to collaborate” with Tencent across a range of areas.