The “One Belt, One Road” infrastructure project presents giant business opportunities for Western companies—if they already have deep ties in China and the region.

With more than $900 billion expected to be invested in roads, ports, pipelines and other infrastructure as part of the project, which spans countries in Asia, Africa and Europe, there is some opposition to China’s heavy-handedness in choosing contractors and suppliers.

At a high-level summit promoting the project China’s President Xi Jinping on Sunday portrayed the country as a committed free trader and pledged more than $100 billion in new financing and assistance. The project, launched in 2013, is based on updating the ancient Silk Road that linked China to Central Asia, Africa, the Middle East and Europe and is intended to better connect China to its exports markets.

The summit—taking place Sunday and Monday in Beijing—is also expected to open up new avenues for Western companies searching for growth opportunities outside their home markets.

Multinationals, such as Honeywell International Inc., HON -1.13% General Electric Co. GE -1.98% and Caterpillar Inc. CAT -0.08% are moving forward with plans to participate in One Belt, One Road. These companies have well-established relationships in Beijing and are poised to benefit.

“OBOR [One Belt, One Road] fell in our lap, as a perfect serendipity,” said Shane Tedjarati, president of Honeywell’s high-growth regions business. The company generates a “significant amount” of money with OBOR-related projects, Mr. Tedjarati said.

U.S. companies could use the business. The percentage of sales outside the U.S. by S&P 500 companies was 44.3% in 2015, the most recent data available, down from 47.8% the year before and an average of 46% from 2009 to 2013. Asian sales fell to 6.77% in 2015 from 7.8% in 2014, according to S&P Dow Jones Indices.

Experience in markets outside of China is a competitive advantage for international companies. While Chinese firms may be the main contractors for projects such as port installations or bridges, they will end up subcontracting to other, often times Western, companies with decades of experience integrating technology across borders, Western firms and experts say.

That expertise combined with strong China relationships is key for Western companies looking to get involved in One Belt. Being able to develop a single, unified network to operate everything from trains, shipping logistics to toll roads is a competitive advantage.

“We are on the ground in almost all of the Belt and Road countries, with local knowledge and understanding, as well as access to technology and deep domain expertise,” said John Rice, president and CEO of GE’s global growth and operations unit.

Since the project spans multiple countries across several continents, Chinese companies may not be able to provide integrated services, such as distributed control systems for industrial plants across all One Belt, One Road regions, said Honeywell’s Mr. Tedjarati. “We can then say ‘Do you know we can also service you in Kenya and in Kazakhstan?’” he said. Honeywell would take on that work. China sales accounted for about 6%—$2.4 billion—of Honeywell’s revenue in 2016.

China’s total value of trade with participating countries reached $953.6 billion in 2016, according to the Belt and Road Portal, a website operated by the Chinese government.

Chinese President Xi Jinping waves at a welcome banquet for the Belt and Road Forum in Beijing on Sunday. Photo: WU HONG/AFP/Getty Images

Caterpillar, the Peoria, Ill., maker of excavators and other heavy machinery, is present in more than 20 OBOR-countries. “We have learnt that these projects are increasingly demanding in terms of timely delivery, quick response, 24-hours technical support and smooth communication,” said Qihua Chen, country manager of Caterpillar in China.

Siemens AG , for example, has a competitive advantage because of its longstanding presence in China and technical experience with various electricity and track standards so that it can operate its trains across several countries, said Müslüm Yakisan, head of commuter and regional trains.

Financing, however, stills works in favor of Chinese, not Western companies, some firms say. Industrial and Commercial Bank of China Ltd., the world’s largest bank by assets, said it makes lending to Chinese firms a priority, as many of these are already existing customers. “We can offer better deals than our Western competitors,” said Xiao Lu, head of corporate banking at ICBC PLC in London.

Siemens therefore offers co-financing and syndicated loans when bidding for a project, said Mr. Yakisan. Siemens during the first half of its 2017 fiscal year reported revenue of €3.25 billion in China ($3.55 billion).

But not all Western companies reap OBOR’s benefits. “We are scratching our heads—where are we getting involved in this?” said Joerg Wuttke, the departing president of the European Chamber of Commerce in Beijing. At the summit Sunday, the U.S. urged China to uphold norms on international bidding.

There is a lack of information around how to get involved in OBOR, said Walter Pitz, operating chief at Steinmueller Babcock Engineering Consulting Co., a subsidiary of Nippon Steel & Sumikin Engineering Co., a Japanese engineering firm. “This is the core reason” why Steinmüller isn’t taking part, Mr. Pitz said. “And, I don’t know anyone that does,” he said.

Getting involved on the back of a major Chinese company is one way forward. ITT Inc., a U.S.-based producer of dampers used in high speed trains, relies on existing connections and technical expertise. Because of supply agreements with Chinese firms such as China Railway Rolling Stock Corp., the world’s largest rolling stock manufacturer, ITT is involved in several OBOR-related projects.

Asia Pacific accounted for 12% of ITT’s global revenue in 2016.

“We have relationships that are tried and tested in China,” said Ryan Flynn, vice president for motion technologies at ITT in Shanghai.

—Richard Teitelbaum contributed to this article.

Write to Nina Trentmann at Nina.Trentmann@wsj.com