Haleh Nematzadeh, 36, claims Ono, 80, tweaked designs from her women's fashion line to produce a men's clothing range, the Daily Mail reported.
The allegations come a few days after Ono debuted her men's clothing line "1969-2012" for Opening Ceremony, which features several see-through and hand-printed items -- two characteristics also prominent in Nematzadeh's garments.
According to the 36-year-old, she met with photographers from Opening Ceremony who promised to return to photograph her clothes but instead went to Ono's team with her ideas.
"They took everything with no shame," the designer said of Ono's team.
Nematzadeh filed a lawsuit in Brooklyn's federal court on Friday, calling Ono's actions a "feeble attempt" to claim the designs as her own.
"She’s trying to put fetish in context, but since when does fetish and John Lennon go together? When you think of the Beatles, you think of doves and trees, not that," she said.
Ono has said her clothing line was inspired on a book of drawings she gave Lennon on their wedding day, adding that they are a tribute to his body.
"I was inspired to create Fashion for Men, amazed at how my man was looking so great. I felt it was a pity if we could not make clothes emphasizing his very sexy bod," Ono's website reads.
Nematzadeh's lawyer said it's not uncommon for big companies to take ideas from independent designers.
"They rip off pieces here and there all the time, but you don’t see up-and-coming artist really trying to fight for their rights," he said.