The party won 47 seats out of the results of the 90-member assembly declared here. It was leading in another seat whose result was yet to be declared.
In a related development, outgoing Chief Minister Bhupinder Singh Hooda submitted his resignation to Governor Kaptaan Singh Solanki.
Hooda held a meeting with senior officers of the state government and addressed the media before submitting his resignation.
Accepting defeat in the assembly polls, he hoped that the new Bharatiya Janata Party government would keep up the pace of development in the state.
The Congress won 15 seats while the Indian National Lok Dal won 19 seats in the assembly polls.
Two seats went to the Haryana Janhit Congress (HJC), one each to the Bahujan Samaj Party (BSP) and Shiromani Akali Dal and five independents won.