In an interview with Portuguese paper Expresso that will run Saturday, the 36-year-old Solo, a Richland native, said Blatter assaulted her just before both of them took the stage at the 2012 Ballon d'Or awards, according to The Guardian.
She said: "It was at the Ballon d'Or, right before I went on stage".
She presented the Federation Internationale de Football Association women's world player of the year award alongside the 81-year-old at the glitzy ceremony.
Hope Solo and Joseph Blatter, FIFA president announce Abby Wambach of United States during the FIFA womens player of the year trophy during the FIFA Ballon d'Or Gala 2013 at Congress House on January 07, 2013 in Zurich, Switzerland.
"After that I did not see him and that was kind of bad", she told the magazine.
Blatter could not immediately be reached for comment by the AP, but the embattled former head of soccer's governing body told the Guardian newspaper: "This allegation is ridiculous". She had to pull herself together quickly to give the award to Wambach. I always felt I'd "handled it' and stood up for myself in those situations, but there were never any consequences for the perpetrators".
"I speak out directly [with people] when things like that happen".
"For years, in the past, female players date and end up marrying their college coaches, which obviously a coach should not be doing, especially with a young player", she said.
Solo added she hopes other women athletes will speak up about their experiences.
The shocking claim was made after she was asked if sexual harassment was as much an issue in women's soccer as it has been in Hollywood. Silence will not change the world! I've seen it amongst players in the locker room.
Blatter also famously argued in 2004 that players could boost the popularity of the women's game by wearing tighter shorts.
Blatter was then one of soccer's most powerful figures; he has since been banned from Federation Internationale de Football Association amid a widespread corruption scandal.