After being discovered by manager Mickey Modern while attending the BRIT School, Heap signed to independent record label Almo Sounds at the age of 18 and later began working with experimental pop band Acacia.

[7] She played music from an early age, first learning the piano due to "wanting attention" as a middle child and realizing, according to her, that "it was something [she] could make a lot of noise with".

[9] Due to being placed a year above children her age, Heap claims she did not get along with many people from the school and spent most of her time in the music room practising piano.

It was there that she recorded her first song to feature her vocals, "Missing You", which was released on the BRIT School's Class of 1994 album and earned her attention from manager Mickey Modern after he saw her performance at a talent showcase.

[20] The record was made with several producers, including English musician Dave Stewart and Sigsworth, and received some critical praise but was a commercial failure, as Almo did little to promote the album.

Heap and Sigsworth remain firm friends and have worked together since the project, including their temporary re-formation in late 2003, when they covered the Bonnie Tyler classic "Holding Out for a Hero" which was featured during the credits of the movie Shrek 2 after Jennifer Saunders' version in the film.

[citation needed] Heap recorded a rendition of the song "I'm a Lonely Little Petunia (In an Onion Patch)" for the seventh episode of the fourth season of the HBO drama series Six Feet Under, which premiered in August 2004.

[citation needed] Also that month, Heap appeared on the soundtrack for the 2005 romantic comedy film Just Like Heaven, performing a cover of the song "Spooky" by American band Classics IV.

[citation needed] In November 2005, Heap wrote and recorded the song "Can't Take It In" for the soundtrack of the fantasy film The Chronicles of Narnia: The Lion, the Witch and the Wardrobe, which was released one month later.

[36] In August 2006, Heap performed a set at the V Festival,[37][better source needed] where it was announced that "Headlock" was to be the third single lifted from the album and released on 16 October 2006 in the UK.

This was her first tour of North America that included a band, incorporating upright bass, percussion, and support acts Kid Beyond and Levi Weaver on beatbox and guitar, respectively.

[citation needed] In October 2008, Heap gave a musical performance in the anti-human trafficking documentary and rockumentary film Call + Response, directed by Justin Dillon.

[48] The third single from the album, "Neglected Space", was created as part of Heap's project with charity organization Clear Village to restore a walled garden in Bedfords Park in October 2011.

[49] She starred in the debut episode of the MTV India musical reality television series The Dewarists, where she recorded "Minds Without Fear", her fourth single from Sparks, with Indian production duo Vishal–Shekhar.

[71] Heap was one of the artists featured in an episode of the 2016 PBS docuseries Soundbreaking and she narrated and composed music for the 2016 documentary Crossing Bhutan, which premiered at the Santa Barbara International Film Festival.

[95] During the COVID-19 pandemic, she launched a self-titled app for fans to view unreleased material and demos and participate in listening parties with her through Discord for a monthly fee, and began work on a project called "Augmented Imogen", meant to be an AI version of herself.

In 2014, filmmaker Christopher Ian Smith[101] made Cumulus,[102] an experimental documentary exploring key elements of Heap's background, personality and music practice.

[105][106] They were inspired by another pair of musical gloves developed by engineer Elly Jessop at MIT which Heap had witnessed during a visit to the university's Media Lab.

[105] In an interview, Heap stated, "The gloves help me embody those sounds which are hidden inside the computer, for me to physicalize them and bring them out so that I can play them and the audience members will understand what I am doing—rather than fiddling around on a keyboard and mouse which is not very clear—I could just be doing my emails.

"[107] The gloves, which eventually came to be known as the Mi.Mu gloves (a name derived from an abbreviation of "me" and "music"),[45] are made from the material Yulex and consist of a hardware board at the wrist developed by Seb Madgwick with an inertial measurement unit used to determine the speed and orientation of the hands, flex sensors over the knuckles, a haptic motor, a removable battery, open palms and LED lights in between the thumb and forefinger which indicate whether or not the user is recording.

[109][110] The gloves also come with a custom software called Glover that can be integrated with music production apps such as Ableton Live and Pro Tools, and use 802.11 Wi-Fi.

Her earlier songs, specifically those from her debut album I Megaphone, were frequently compared in the media to those of fellow singer-songwriters Tori Amos, Kate Bush and Alanis Morissette.

[130] Heap has been cited as a musical inspiration by a number of artists and groups, including Ariana Grande,[131] Bebe Rexha,[132] Ellie Goulding,[133] Kacey Musgraves,[134] Pentatonix,[135][136] Chloe Bailey,[137] Empress Of,[138] Dawn Richard,[139] Jamila Woods,[140] Muna,[141] Mree,[142] Woodes,[143] Ben Hopkins,[144] Matthew Parker,[145] Red Moon,[146] Michelle Chamuel,[147] Chaz Cardigan,[127] Laura Doggett,[148] GoodLuck,[149] Kool Kojak,[150] and Stars and Rabbit.

[citation needed] In 2011, Heap played a benefit concert in Christchurch, New Zealand, to help rebuild the Unlimited Paenga Tawhiti High School following a severe earthquake which destroyed a large portion of the city earlier in the year.

The concert was held at the Burnside High Aurora Centre, also featuring performances from Roseanna Gamlen-Greene, and The Harbour Union including The Eastern, Lindon Puffin, Delaney Davidson and The Unfaithful Ways.

Triggered by monsoon rains, the floods left approximately one-fifth of the country of Pakistan under water, affecting over 14 million people and damaging or destroying over 900,000 homes.

Teaming up with Richard Branson's Virgin Unite and Vokle.com, Heap and Ermacora created a webcast/online fundraiser to raise awareness and money for those affected by the floods.

Hosted by comedian, creative and Internet personality Ze Frank, the webcast included a series of conversations with Cameron Sinclair of Architecture for Humanity, Gary Slutkin and Anders Wilhelmson (and later Richard Branson and Mary Robinson), with live performances by musicians Ben Folds, Amanda Palmer, Kate Havnevik, KT Tunstall, Josh Groban, Kaki King, Zoe Keating and Mark Isham.

The premise of Live 4 X thus established, Heap has since continued to refine the model, organize, host and perform a number of charitable, live-streaming concert events.

Following the Great East Japan earthquake and tsunami of 2011, Heap told Washington Times Communities journalist and recording artist Jennifer Grassman that she intended to continue organising Live 4 X events to benefit various charitable causes.