The clothing and footwear group, which trades as JD Sports, Chausport, Size, Bank and Scotts from over 530 stores, made an underlying pretax profit of £19.4m in the six months to 31 July, up from £14.2m in the same period last year.
"The result for the full year remains very dependent on the sales and margin performance in December and January," the firm said in a statement.
Group revenue increased 18.5 per cent to £383.9m.
Sales at UK and Ireland stores open over a year rose 2.8 per cent over the half and were up 2.7 per cent for the four weeks to 28 August.
The firm, which ended the period with net cash of 34.5 million pounds, is paying an interim dividend of 3.8 pence, up 15.2 percent.