The popular online star is thought to have died after a horrific collision close to her home in South London on Friday morning.
Her death was confirmed in an Instagram post that read: "Hi everyone. This is a horrible thing to have to say over Instagram but we know many of you were expecting to see Emily today and this is the only way to contact you all at once.
"Emily was involved in an accident yesterday and passed away. We all loved her to bits and she will never be forgotten.
"She has touched so many lives it's hard to imagine things without her. She was a very special person xxx."
Since the sad news was announced in that statement, tributes have been flowing in for the star who presented Oh S***, I'm 30 on Channel 4, as well as hosting a number of online shows. She also had 340,000 subscribers on YouTube.
She founded the channel 10 Reasons Why, on which she interviewed a number of high profile celebrities such as Hugh Jackman, Eddie Redmayne and Amanda Seyfried.
TV presenter Davina McCall said: "My heart goes out to Emily's family and friends. Such a shock. Sending you love and prayers."
Reality TV star Calum Best added: "Jesus Christ no way this is so sad I'm so sorry."
Made In Chelsea star Ashley James commented: "Sending you all so much love. So devastated."
Hartridge was pronounced dead at the scene of the collision at around 8.30am on Friday morning.
Police are investigating the incident, but no arrests have been made.
Before her death, Hartridge revealed that she had frozen some of her eggs after discovering that she had low fertility levels.
She had also recently entered into a relationship with fellow personal trainer Jacob Hazell and shared a picture of the pair kissing as one of her final Instagram snaps.
The post was entitled: "10 REASONS TO HAVE A YOUNGER BOYFRIEND."
It read: "And I know for many women over 30 they might be unsure about dating someone that much younger but let me tell you......IT IS AWESOME."
The young couple had recently moved in with one another. Hartridge recently spoke to The Sun about her relationship with Hazell.
She said: "Two weeks before I was due to freeze my eggs in November 2018 I met Jake, 27, a fellow PT. We hit it off and I told him about getting my eggs frozen. Thankfully, he was very open-minded about it.
"However, I'd already started injecting myself with hormones, which didn't give us the easiest start to our relationship.
"It didn't affect our sex life, but my moods were all over the place, and some days all I wanted to do was curl up into a ball. But Jake was so supportive and even came with me for my first procedure."
Police investigations are ongoing.