Adidas said in a statement that its chief executive Herbert Hainer met Wanda Group Chairman Wang Jianlin in Beijing "to discuss the prospect of a future strategic collaboration."
As part of the agreement, Adidas would sponsor two of Wanda's Ironman events in China, "as well as work with the Chinese conglomerate to help develop football and basketball at all levels," the statement said.
"Adidas and Wanda also agreed to deepen their commercial relationship," it added.
"China is one of the most important markets for Adidas globally. We have strengthened our position in China considerably in recent years," said CEO Hainer.
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"We are now looking forward to working with Wanda Group, one of China's largest and most respected companies as well as a powerful name in the world of sport."
The Chinese cities of Hefei and Xiamen are scheduled to host two Ironman events later this year.
Wanda acquired the Ironman brand along with its parent company, the World Triathlon Corporation (WTC), in August 2015.
Adidas is the world's number one maker of soccer equipment, with a market share of 37 per cent in 2014, ahead of arch-rival Nike with 29 per cent and is targeting sales in this sector of 2.5 billion euros this year.
Wanda, owned by one of China's richest men Wang Jianlin, last year acquired a 20-percent stake in the Spanish football club Atletico Madrid and in March became one of the main sponsors in the Fifa international football federation.