The Essex-based group, which has more than 750 convenience stores plus 544 newsagents, said earnings in the six months to May 25 rose 10.9% to £15.9 million, although costs from its recent stock market flotation meant it racked up a bottom-line loss of £4 million.
McColl's has been rolling out a store transformation programme and working with the Post Office on its "local" model, where more services are offered across retail counters .
It has completed 40 of the conversions so far and hopes to complete the whole of the 191-strong estate by the end of the current financial year.
During the period, McColl's acquired 23 stores, converted 20 newsagents to food & wine formats and upgraded another 98 convenience stores.
The business, which recently launched loyalty card scheme Plus to reward repeat customers, said sales in its upgraded stores were around 2.4% higher.
The group opened its 750th convenience store in June and plans to have 1,000 by the end of June 2016.
McColl's was valued at £200 million when it listed on the London market in February, although it currently trades 11% below its 191p launch price.
Chairman James Lancaster said the chain delivered "solid progress" in the half year but added that the outlook for the market remained "competitive, with increasingly value conscious customers."
In order to comply with corporate governance, Mr Lancaster will now just act as the chief executive. John Coleman, currently non-executive director and deputy chairman, will become non-executive chairman.