The 'Fidelity' singer told the BBC that she is a big fan of Nash as a person and an artist.
Spektor said: "Kate Nash is just lovely. She's a very sweet and talented person and it's amazing that she considered that I had anything to do with anything.
"It's a real honour and it's really cool."
She added that one of her own key influences was The Moldy Peaches' Kimya Dawson, whom she described as a "very special musician".
Spektor will play the Serpentine Sessions festival in London's Hyde Park on June 29.