The coffee shop and restaurant firm enjoyed a strong first quarter, with group like-for-like sales up 4.5%.
Within that, like-for-like sales were up 8.4% at Costa Coffee, and 4.3% at budget hotel chain Premier Inn.
Whitbread opened 35 new UK stores over the period; 29 in UK Retail and 6 in Costa Enterprises.
The group said it plans to open a further 4,200 Premier Inn rooms, eight joint site restaurants and 350 new Costa stores this year.
Costa is already Britain's biggest coffee shop brand with almost 1,400 shops and has a further 800 units in 25 overseas markets, including China and India.
Andy Harrison, Chief Executive of Whitbread, said: "Our plans for profitable growth are well established, supported by our strong balance sheet."
But he added: "For the second quarter we face tougher comparatives against a strong result last year, together with the uncertain impact of this summer's major sporting events."
In April, Whitbread posted a rise in full-year profit and said Premier Inn had enjoyed sales growth since the start of the new financial year, recovering from a dip over Christmas and in the early part of 2012.