The newfound success comes after the song was included in the hit Netflix show Stranger Things.
The song is an integral plot motif for one of the characters, Max Mayfield, during season 4 of the show.
Thanks to Stranger Things, a new generation of listeners have now discovered the work of Kate Bush, sending the 1980s song soaring back up to the top of the charts.
This is the longest time a song has taken to reach the top of the charts, after its release nearly 37 years ago.
Bush revealed that she was already a fan of the show herself, even before she found out her song was to be part of it.
"It's such a great series. I thought that the track would get some attention, but I just never imagined that it would be anything like this," she said.
"The Duffer brothers created the series and actually we watched it from the first series onwards, so I was already familiar with the series. And I thought what a lovely way for the song to be used in such a positive way. You know, as a kind of talisman almost really for Max. And yeah, I think it's very touching, actually."
The singer also revealed that she hadn't listened to Running Up That Hill "for a really long time", adding: "I never listen to my old stuff."
Kate Bush last performed Running Up That Hill live in 2014, for her theatrical London concert series Before the Dawn.
The song is expected to remain at the top of the charts for a while and Stranger Things co-creator Matt Duffer has already said the hit will play a part in the season finale as well.
"There's an epic Kate Bush moment in the finale that we weren't expecting, that we kind of discovered as we were editing," Duffer said.
"The sequence was really cool and we were happy with it, but it was missing a little something. And I was like, 'Well, let's try Kate. Because when has Kate let us down?' And it just took it to this new height. It's arguably the most epic Kate Bush moment. It comes back in a major way."
