The 19-year-old came through 6-4 6-2 in 87 minutes to earn her first victory of the North American hard court season.
“It definitely feels really good to get a win here in DC,” said Raducanu.
“After not playing for quite a bit after Wimbledon or many matches at all this year, I think it’s a really nice feeling just to get on the board.”
The world number 10 will face Colombia’s Camila Osorio in the Washington Open second round as she continues to build up to the year’s final Grand Slam, which begins on 29 August.
Meanwhile, Britain’s Dan Evans secured his place in the third round with a 6-1 6-2 victory over compatriot Kyle Edmund, and will now face America’s Taylor Fritz or Australian Alexei Popyrin.
“My focus was very good,” said 32-year-old Evans. “It’s always nice to start a new swing off with a win and it’s nice to be through to the third round.”
Murray beaten in Australian Open first round
Meanwhile, Britain’s Jack Draper suffered a 6-4 6-2 defeat by Russian top seed Andrey Rublev.
Wimbledon runner-up Nick Kyrgios was also in action for the first time since losing on his Grand Slam final debut, the Australian beating American Marcos Giron 6-3 6-2.
At the Silicon Valley Classic in California, Japan’s four-time major winner Naomi Osaka returned for the first time since May with a 6-4 3-6 6-1 win over China’s Zheng Qinwen to set up a meeting with American 18-year-old Coco Gauff, who beat Ukraine’s Anhelina Kalinina 6-1 6-0.
“What’s always impressed me about Coco is her mentality,” said Osaka, 24. “She’s improving every year, so I think there’s a lot that she’s learning and it’s only a matter of time before she wins a Slam.”