The £220m deal, announced last month, was formally ratified by Trinity Mirror shareholders at a general meeting today.
A total of 235,558,950 voting shares were cast in favour of the deal with 10,641 voting against.
The number of votes cast represented more than 83pc of the 280m-plus shares in circulation.
It means the sale has now been completed and the two companies have become a single legal entity. There has been no reference made to the competition authorities.
The newly-merged company is now the biggest local newspaper publisher in the UK, with the main regional daily titles in 14 of the country’s biggest centres of population in the UK.
In a regulatory announcement, Trinity Mirror said: “On 28 October, Trinity Mirror plc announced the proposed acquisition of all of the shares in Local World Holdings Limited not already owned by the Company.
“Following shareholder approval of the Transaction at the General Meeting as announced earlier today, Trinity Mirror is pleased to confirm that it has completed the acquisition.”
The purchase price paid by TM for the 80pc of shares in LW it did not already own was £154.4m, plus a further £33m in other costs, valuing the company at £220m overall.
Dealing in shares in the newly combined company is expected to begin on Monday.