The chain, which was sold to Chinese private equity firm Hony Capital in 2014 for £900m, said turnover grew to £267.2m in the 28 weeks to 10 January compared with £230.6m the same time last year.
Like-for-like sales in the UK & Ireland edged up by 0.5 per cent, helped by the launch of new Autumn season menu and the introduction of Christmas specials.
Meanwhile earnings before interest, tax, depreciation and amortisation (ebitda) rose by three per cent year-on-year at £56.4m.
Pizza Express has been ramping up its international expansion since its sale to Hony Capital and bought back the franchises for the business in China and the United Arab Emirates last year.
It opened 12 new sites overseas during the first half and 13 in the UK and Ireland, where it now operates over 450 restaurants.
The group also recently snapped up Firezza, a gourmet pizza delivery company with 17 sites across London and branched away from pizza altogether after opening a new chicken restaurant, called Reys, in Cambridge.
Richard Hodgson, chief executive of Pizza Express, said: “Despite a more challenging market backdrop, PizzaExpress has performed well in the first half of the year and the developments in our new delivery offer and the initial success of Reys have been particularly exciting.
"Our performance outside London was broad based across the UK and continued to be driven by an increase in number of covers," he added.