At 250-metres long and weighing 130 tonnes, the fatberg, described by Thames Water as one of the largest it had ever seen, is six times longer than London Bridge and as heavy as 11 London buses, according to the BBC.
The company's head of waste networks Matt Rimmer told the Beeb: "It's a total monster and taking a lot of manpower and machinery to remove as it's set hard."
Eight workers will break up the mass with high-pressure hoses, suck up the pieces into tankers and take it to a recycling site in Stratford.
Thames Water launched a campaign earlier this year to to encourage food outlets to effectively manage waste fats, oils and grease.
It said its campaign would mainly target restaurants and fast food retailers, off the back of research carried out over two years in Oxford which revealed that 95% of food establishments visited were contributing to sewer blockages by having inadequate or no kitchen grease management.
“There’s a clear link between our fatberg hotspots and high concentrations of food outlets, so it’s important we do all we can to help," said Thames Water's former head of waste managment, Steve Spencer.