Melrose has succeeded in its hostile bid to take over GKN for £8.1 billion after securing the backing of the engineering giant's shareholders.
A total of 52.43% investor votes were cast in favour of the deal going ahead as of 1pm, above the 50% plus 1 share threshold.
In a statement Melrose's chair, Christopher Miller, said the company were "delighted and grateful to have received support from GKN shareholders for our plan to create a UK industrial powerhouse with a market capitalisation of over GBP10 billion and a tremendous future.
"We are looking forward to working with GKN's talented workforce and to delivering for customers and all stakeholders. Melrose has made commitments as to investment in R&D, skills and people and we are very excited about putting these into action.
"Let me assure you that GKN is entering into very good hands."
Melrose's victory brings to a close a bitter battle that has raged since January, although there are likely to be renewed calls for Business Secretary Greg Clark to intervene in the deal.
He has already called for "binding" agreements over Melrose's proposals for GKN.
ITV News Business Editor Joel Hills says the Government is unlikely to be able to block the deal.
Melrose has stressed its commitment to improving "not only GKN, but the UK economy", committing to keeping the firm listed in London and headquartered in the UK as part of a five-year pledge.
Mr Miller added: "We would like to thank our shareholders for their continued support of the Melrose strategy thus far.
"We are full of enthusiasm as we begin this next stage of the Melrose story and look forward to creating substantial value for our shareholders, old and new."
Shares in GKN rose 7% following the news.
But Melrose's takeover will spark fears for jobs after Airbus, GKN's largest customer, earlier warned it could not give any new business to the firm if the deal with the turnaround specialist went ahead.
Unions and MPs have also warned over asset stripping and flagged national security concerns, claims which Melrose has rejected.
Unite is calling for the Government to intervene on national defence grounds and is vowing to hold "Melrose's feet to the fire over concessions it's made in recent days and seeking concrete guarantees on job security".
GKN ultimately attempted in vain to fight off Melrose's advances, despite chief executive Anne Stevens describing the takeover as "high-risk" and the offer not coming close to reflecting true value.
Its counter measures, which included a deal to sell its automotive division Driveline to US firm Dana, fell on deaf shareholder ears.
GKN became a target following profit warnings in October and November after problems at its US aerospace division sent shares tumbling.
GKN is headquartered in Redditch and has its biggest factory in Filton near Bristol, where it employs 1454 workers.
Jack Dromey, MP for Birmingham Erdington, where GKN has a plant, had opposed Melrose's hostile takeover of GKN, calling the deal "a bleak day for British industry.
"The takeover by Melrose makes a mockery of any talk by Government of an industrial strategy."
Other plants in the UK include Cowes, Birmingham, Luton, Telford, Kings Norton, Portsmouth, Uxbridge, Leek and Oxford.
GKN has a history that dates back to the 1900s and was instrumental in wartime manufacturing.
During the First World War, it was heavily involved in making steel for military purposes, such as shells.
After the outbreak of the Second World War, GKN produced Spitfires and specialised tanks for the D-Day landings, as well as millions of steel helmets.