The assurance came when a 27-member delegation of the ex-servicemen called on Parrikar at Kota House here, his residence for the time-being.
A rally was also held here by the ex-servicemen, seeking early implementation of the scheme.
Defence sources said Parrikar assured the ex-servicemen of rolling it out at the earliest.
He said he is working hard on it and the Ministry will send its views to the Finance Ministry by February 17.
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"I will do my work," he was quoted as telling the delegation.
Maj Gen Satbir Singh (retd), Chairman of Indian Ex-Service Movement, said the meeting with Parrikar was "positive".
He said that the Minister has given assurances to the delegation on four major issues relating to the scheme, including "getting approval from the Finance Ministry before the Budget this month".
One rank, one pension scheme has been a long-standing demand of the over 2 million ex-servicemen in the country.
It seeks to ensure that a uniform pension is paid to defence personnel who retire at the same rank with the same length of service, irrespective of their date of retirement.