Katy Perry has shared an emotional tribute to her late friend Angelica Cob-Baehler, calling the music executive one of her "biggest champions and realest friends".

Angelica died on 21 November (18) aged 47, after a lengthy battle with cancer. Alongside a gallery of pictures of her and her pal on Instagram, Katy wrote a heartfelt caption explaining the bond she shared with Angelica, who worked with artists such as John Mayer and Thirty Seconds to Mars over her 25-year career and was instrumental in forging a career for the I Kissed a Girl star.

"Six days ago, one of my biggest champions and realest friends, Angelica Cob-Baehler moved on from this place," Katy began her tribute. "She was one of the strongest women I have ever known - fighting her cancer like friggin’ Rocky, enduring chemo, immunotherapy, a tracheotomy, feeding tubes for months on end, and experimental cancer treatment trials. I watched her go through many stages for over a year, but a few things remained constant: her sarcastic/wicked sense of humour, her positive outlook, and the incredible love she had for her family."

Katy and Angelica first met when the latter was a Vice President at Columbia Records, the label Katy had recorded an album which they were delaying the release of. So when Angelica moved to Virgin Records in 2005, she "stole all the Katy files", remembering the daring move in a video also shared as part of the singer's tribute. She then launched a campaign to bring Katy to her new label, after Virgin merged into the EMI Music Group, and eventually was responsible for the singer signing with Capitol Records.

"She was like a big sister to me, showing me the ropes and always having my back. She never became a yes-person and was quick to check me when I needed checking - that was family," Katy continued. "I’ll never let them forget that Angelica embodied the angel in her name, was a woman of incredible integrity and character, a massive giver, and a DOPE human being."

The 34-year-old urged her followers to donate to Angelica's favourite charity, Generosity.org, in her honour, and promised that she would help look after her husband Chapman Baehler and their two daughters in the wake of her death.

"She may be gone from this place, but she will never be forgotten. Rest in power, my angel, and don’t worry, we got Chapman and the girls. #RIPGeli," Katy concluded the heartbreaking post.