The 11.4-km metro operations are likely to start in the next one week, as the company had earlier said it would start services "within seven days of such approval" coming.
PTI has seen the copy of the Railway Board approval.
But Mumbai Metro One, however, said it is yet to receive any communication from the board in this regard.
"We have not yet received any communication from the board. But we are prepared to commence operations within seven days from the receipt of the approval from the Board," Metro One chief executive Abhay Mishra told PTI.