The discussion centred on children in armed conflicts, an issue both countries are concerned with and one that will be debated by the UN Security Council on Tuesday.
"We agreed that we should find a way to cooperate over the question of children in armed conflict. It's something I got the impression she feels very strongly about," Wallström told Swedish news agency TT.
They also discussed the situation in Afghanistan and South Sudan, as well as other issues relevant to the Security Council agenda:
"Haley is a strong and constructive voice in the USA and she feels very strongly about what she does. It was nice to meet her".
Haley took up her position in January, and there has been speculation about her political ambitions, including that she aims to be secretary of state.
Wallström said she would like to have a good relationship with the diplomat going forward:
"This was a good meeting in the sense that we could get to know each other a bit and speak about what is closest to her heart, and also a little about what our priorities are, without going into detail".