The event will be held next month (Sunday 7 April) and see more than 250,000 people line the river banks to watch the race.
Eight pubs in Putney, south-west London, will use reusable cups this year, which customers can reuse or return to pubs for them to use again.
The initiative was organised by the Positively Putney business improvement district (BID).
Figures from the group show that up to 300 tonnes of rubbish is recovered from the River Thames every year, with single-use plastics making up almost 80% of this.
Pubs will use the cups on football match days throughout the rest of the year.
Positively Putney BID executive director Nicola Grant said: “The annual Boat Race, starting at Putney Bridge, is one of London’s biggest sporting events, attracting hundreds of thousands of visitors to our riverbanks every year.”
“I’m proud that this year we’re teaming up with Putney’s pubs to drastically cut the use of plastics by serving pints in reusable cups.”
She said if each of the 14,000 cups were used just a few times, some 50,000 single-use plastics that would end up in the river or landfill would be prevented in just one day.
“Putney is a great example of the community coming together to clean up the environment," she added.
Young’s brewery’s director of marketing, Gillian McLaren said the boat race was a busy trading day for its pubs in the area.
“We’re very pleased to partner with Positively Putney BID and help keep the river clean by serving our customers in environmentally friendly, reusable cups,” she added.
The initiative was organised with the help of In The Drink, a not-for-profit scheme working to cut single-use plastic on the riverside.
In The Drink’s co-founder Alison Baker said it wanted to phase out the use of disposable cups by the riverside.
She said: “Investing in reusable cups for the Boat Race and beyond, while still keeping the drinks flowing, sets a great example for other riverside organisations to follow this summer.”