The Lionesses thrashed Wales 6-1 on Sunday (13.07.25) to book a quarter-final meeting against Sweden later this week and Toone believes that the team are finding their groove at the tournament.
She told ITV Sport: "They should be scared."
England have overcome defeat in their opening game to progress from the tournament's toughest group but Toone is ready for another challenging game against the Swedes on Thursday (17.07.25).
The Manchester United star said: "It's going to be a difficult game. We watched Sweden the other night, and they were really good - a very good counter-attacking team. We just need to be on our best game. We have been these past couple of games."
Toone was among the goal scorers as England earned a dominant win over Wales and was pleased with the way the team performed against the underdogs.
She said: "We were really good. It's always hard to play against a team that sits in a low block and there's not a lot of space for us, but I think we tired them out, and it was nice that we got early goals in the first half. We really enjoyed the game."
England coach Sarina Wiegman was also happy with the way her team played.
She said: "We scored six goals and a big part of the game we dominated, a very good game. Playing well is the most important, who scores is not that important."
Wiegman has been particularly impressed by how the players have responded to the disappointment of losing their opening game against France.
The Dutch coach said: "I'm very happy. We knew ahead of this tournament how hard this group was going to be, then when you lose the first game there is massive urgency to win the other two.
"It gave a lot of learnings with the team and it brought us together - I think that's pretty good."