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Jeffrey Immelt, center, the chief executive of General Electric, at an Alstom site in France last year after the deal was announced. Credit Johann Rousselot for The New York Times 

PARIS — General Electric on Tuesday overcame the last big hurdle to the largest acquisition in its history, a $13.5 billion deal for the power business of Alstom of France, as European officials agreed that the American company had adequately addressed their antitrust concerns.

For General Electric and its chairman and chief, Jeffrey R. Immelt, the proposed deal is part of the company’s renewed emphasis on industrial businesses after a risky diversification into finance by his predecessor, Jack Welch.

With the pieces of Alstom it aims to buy, G.E. means to extend its global leadership in the business of providing electrical utilities with generating equipment and power-grid distribution systems. G.E. and competitors like Siemens see big opportunities in that business as the world moves away from coal and toward cleaner natural gas, solar and wind energy.

G.E.’s securing a go-ahead for the Alstom deal is all the more significant at a time when European officials are holding American multinational companies, including Google and Amazon, to intense regulatory scrutiny.

But approval was by no means a certainty, after the European Union’s antitrust chief, Margrethe Vestager, opened an investigation into the deal in February, warning that the combined company’s dominance might lead to higher prices and fewer options for customers.

Ms. Vestager’s office approved the deal only after G.E. agreed to sell some of Alstom’s European assets to Ansaldo Energia, an Italian engineering company that builds and services power plants.

Announcing the approval on Tuesday, Ms. Vestager said the conditions showed that “Europe is open for business,” but also that “you cannot buy yourself into a monopoly.”

The divestitures to Ansaldo would avoid “a great risk of choice going down and prices going up,” Ms. Vestager said at a news conference in Strasbourg, France.

The United States Department of Justice’s antitrust arm said on Tuesday that it, too, would approve the merger, having coordinated its efforts with Ms. Vestager’s office, provided the companies met the conditions detailed by the European Commission.

Mr. Immelt devoted more than a year to careful corporate diplomacy in pursuing his goal — first in winning the French government’s endorsement and then, in a more protracted process, gaining approval from European antitrust regulators in Brussels.

The French government, which considered Alstom one of its “national champion” corporations, had initially balked — and even tried to broker an alternative deal between Alstom and Siemens of Germany. In the end, Paris agreed to G.E.’s offer, but only after arranging to have the French government hold a stake in the merged businesses.

After accounting for the French government’s investments, G.E. will be putting around 8.5 billion euros, or about $9.5 billion, into the deal.

Mr. Immelt also succeeded in Brussels where Mr. Welch had failed in spectacular fashion more than a decade ago. In July 2001, European officials blocked General Electric’s planned $42 billion acquisition of Honeywell International on antitrust grounds. It was the first time European antitrust authoried had halted a deal between American companies that had been cleared by American officials.

In a telephone interview on Tuesday, Mr. Immelt played down the extent of G.E.’s concessions to win Ms. Vestager’s approval, saying they were “well in line with what we expected.”

“Business people live in a world where regulators are stronger, not just in Europe,” he said, noting that companies must cooperate as a cost of doing business.

The Alstom assets, in particular the gas and steam turbine businesses, should strengthen G.E.’s footing in emerging markets like China and India, where air pollution from coal power is a menace to public health. The American company is also obtaining sophisticated technology in renewable energies and power-grid infrastructure, as well as the French company’s expertise in power-plant design.

Alstom’s power unit makes equipment for generating and distributing electricity for utilities across the globe.

But the main prize for G.E. is Alstom’s heavy-duty gas turbines business, which holds lucrative contracts worldwide for servicing installed power plants. Because G.E. is already the world leader in that field, its main rival in Europe, Siemens, had argued to antitrust officials that the deal would leave too much of that market in the hands of the American company.

On Tuesday, a Siemens spokesman, Alexander Becker, declined to comment.

The Alstom assets to be hived off to Ansaldo include two models of gas turbines and various service contracts in Europe. Ansaldo will also buy Alstom’s Power Systems Manufacturing unit, which makes parts for servicing gas turbines.

Ms. Vestager said at Tuesday’s news conference that the conditions she had agreed to with G.E. were meant to foster the emergence of another European energy technology company.

“For us it was very important that a strategic part of the Alstom business was divested and here we have an upfront buyer in Ansaldo, an Italian company,” Ms. Vestager said. “We find that even if Ansaldo is not the strongest player in the market right now, this gives them a fighting chance and it ensures competition in the European market for heavy-duty gas turbines,” she said.

Steven Winoker, an analyst at Bernstein, estimated that the assets G.E. was selling to Ansaldo generated about $300 million in annual revenue.

“The E.U. needed to have a viable third competitor,” he said, and Ansaldo, though currently a relatively small player, is obtaining assets that “at least gives them a shot at building that business.”

G.E., meanwhile, comes out of the deal with its global scale intact and an improved competitive position, Mr. Winoker said.

Linking with G.E. is an acknowledgment on Alstom’s part that it did not have the scale to continue competing independently in the face of a weak European market and rising competition from Asian producers of power systems.

Alstom agreed in April 2014 to negotiate a sale of its power assets to G.E. The two companies agreed that Alstom’s transport business, which makes high-speed trains like the T.G.V. in France, and other types of rail cars and equipment, would not be part of the agreement and would continue to stand alone.

When the French government, led by President François Hollande, challenged the initial proposal, Mr. Immelt worked with French officials to modify it to Paris’s liking, agreeing to form several joint ventures with the French state.

Throughout, Mr. Immelt worked to ensure that G.E. would walk away with the gas-turbine business, saying that he was open to discussing anything as long as the deal continued to make economic sense.

“For us the strategic interest remains the same,” Mr. Immelt said on Tuesday. “Financially, it’s better than we’d anticipated back in April 2014.”