Jeremy Corbyn will impose a fresh three-line whip on his MPs to back triggering Article 50 at the third and final reading of the bill.
The news comes from a Labour source quoted by the Press Association. The third reading is set to take place on Wednesday.
A source has also said that the move by Corbyn was agreed by the shadow cabinet, ITV reports.
The Labour leader was previously criticised for imposing a three-line whip during the first vote on the bill in the Commons, with many suggesting a free vote would have been more appropriate for such a divisive issue.
He has since faced further censure over Diane Abbott, a close ally, who missed the vote due to illness, with some suggesting her absence was tactical and many Labour MPs calling for action against the shadow health secretary.
A total 47 Labour MPs went against the three-line whip in the first Article 50 vote, however whether they face any consequences for this remains to be seen.