Through a translator, Baysa told
WBZ that she is "very happy" and "very lucky."
"To win Boston is not easy," she said.
Tirfi Tsegaye of Ethiopia was second in 2:30:03, while Kenyan Joyce Chepkirui was third (2:30:50).
American Tatyana McFadden won the women's wheelchair division for the fourth consecutive year, while Marcel Hug of Switzerland won the men's wheelchair race, defending his 2015 title.
While she crossed the finish line with no other competitors in sight, McFadden didn't lead the entire way. She admitted after the race in an on-air interview on NBC Sports Network that she got nervous around the fifth or sixth mile before taking the lead in mile nine.
"I just wasn't catching the rest of the pack as fast as I wanted to," McFadden said. "But you know what? I just needed to remember why I was running, to stay relaxed. The race is 26.2 (miles), and it's a long way to go."
The top American male finisher was Zachary Hine, who finished 10th in 2:21:37. The first American to cross for the women was Neely Spence Gracey, who finished ninth in a time of 2:35.
Marathon bombing survivors take part
The 120th running of the historic race took place under heavy security, three years after double bombings near the finish line left three dead and at least 264 injured.
Leading off this year's marathon were the mobility impaired runners, which included bombing survivor Adrianne Haslet. A professional ballroom dancer, Haslet lost a leg in the bombing three years ago. She is one of 21 survivors competing in this year's race. It's her first time running a marathon.
After about 10 hours of running, she stepped across the finish line on her prosthetic leg and lifted her hands in triumph. Buoyed by the people of Boston who cheered her on, she even got a shout-out from President Barack Obama whose account tweeted: "Terror and bombs can't beat us. We carry on. We finish the race!"
In a special moment last year, Haslet's two brothers ran the race, and she joined them at the finish line. On Friday, she threw out the ceremonial first pitch at Fenway Park before the Red Sox played the Toronto Blue Jays.