Solo, whose legal name is Hope Amelia Stevens, is being held without bail on two counts of fourth-degree assault, according to South King County's inmate locator database.
According to The Seattle Times, police say that the soccer star, 32, allegedly hit her sister and nephew during a family gathering at her Kirkland, Washington, home.
"There was a big party going on at her house. It was an out-of-control situation," Kirkland police spokesman Lt. Mike Murray told the paper.
Officers were called to Solo's home following reports of an assault and a noise disturbance. According to police, during the party, the former Dancing with the Stars contestant allegedly struck both her sister and nephew.
"There were visible injuries on them," Murray said.
Solo, who made headlines when she accused her DWTS partner, Maksim Chmerkovskiy, of slapping her during a rehearsal, was involved in a domestic-violence incident with her then-fiancé, Jerramy Stevens, in 2012.