The company, which was founded by hockey and jazz enthusiast Peter Boizot, said it will open six restaurants in the next three months in Dublin, York, Leamington Spa and three more in London.
"It's not quite like the late 1980s but people seem to be a bit more confident about eating out again," managing director David Page said.
"On flotation in 1993 we thought we would get to 120 restaurants but now we think the UK could stand 150. We have started to open `in-fill' outlets and they are not cannibalising the existing sites. For example, we opened one London restaurant that was only a quarter of a mile away from another outlet and both are doing fine."
Pizza Express now has 41 company-owned outlets and 39 franchise restaurants.
The group has also refurbished several outlets and this month acquired two franchised restaurants for a combined price of £735,000.
Mr Page announced the expansion programme as he unveiled a bullish set of figures for the six months to 31 December. Pre-tax profits rose by 37 per cent to £3m on sales that were up by a third to £10.25m. Like-for- like sales grew by 7 per cent over the half year and Christmas trading in the Nottingham and Cheltenham restaurants was up by 41 per cent on the previous year.
The warmer autumn weather also helped, as milder temperatures encourage people to dine out, the company said.
Cash balances stood at £3.6m at the end of the half year and the company said it would use the strong cash flow from existing outlets to fund its expansion programme. The half-year dividend was raised by 20 per cent to 0.6p, while the shares dipped by 1p in a declining market to 130p.