About Octopus Energy
Octopus Energy is the UK's largest domestic energy supplier by customer accounts, serving around 7.7 million UK households as of 2026. The company was founded in 2015 by Greg Jackson with backing from Octopus Group, a British investment and asset management business headquartered in London.
Octopus grew rapidly from its launch, passing one million UK customers by 2019 and accelerating further during the energy crisis of 2021 to 2022 when it absorbed customers from a series of failed suppliers including Bulb Energy (1.5 million customers) and Avro Energy. It also acquired Shell Energy's UK retail customer base in 2024, which added approximately 1.3 million accounts.
The company operates its own proprietary energy technology platform called Kraken, which handles billing, customer management, and smart tariff operations. Kraken is also licensed to other energy suppliers and utilities internationally, making Octopus both an energy retailer and a technology business.
Octopus Energy Group is privately owned. The majority shareholder is Octopus Group. Other shareholders include Origin Energy of Australia, Tokyo Gas of Japan, Generation Investment Management of the United States, and the Canadian CPP Investment Board, all of which have invested as the group has expanded internationally.
Tariff types offered
Octopus offers one of the widest range of tariff products of any UK supplier.
Fixed rate tariffs lock in unit rates and standing charges for a defined period, typically 12 months. Octopus has at various points offered fixed tariffs with no exit fees, which allows customers to leave early without penalty. Check current terms when comparing.
Flexible Octopus is the standard variable tariff, subject to the Ofgem price cap. Octopus has a published commitment to keep its Flexible rates marginally below the full cap level.
Octopus Tracker is a wholesale-linked tariff where unit rates change daily based on the previous day's wholesale energy market prices. It is a different structure to both fixed and standard variable tariffs.
Agile Octopus is a half-hourly time-of-use tariff where rates vary by the half hour in line with wholesale electricity prices. It requires a smart meter capable of half-hourly reads and suits households that can shift consumption to cheaper periods.
Intelligent Octopus Go is an EV tariff offering a cheap overnight electricity rate during a smart six-hour window, designed for overnight vehicle charging. A compatible smart meter and in some cases a compatible EV charger are required.
Cosy Octopus is a time-of-use tariff designed for heat pump households, offering cheaper rates during periods when renewable generation is high.
Octopus Flux and Outgoing Lite are tariffs designed for households with solar panels and battery storage.
Prepayment options are available through Octopus Key and Card tariffs.
Contact information
Phone: 0808 164 1088
Website: octopus.energy/contact
To compare current tariffs from Octopus Energy alongside other UK suppliers, use the comparison tool below.
Priority Services Register: available for customers who need additional support due to age, disability, or medical dependency.
Trustpilot rating
Octopus Energy holds one of the highest Trustpilot scores among UK energy suppliers, with a rating above 4.7 out of 5 based on a large volume of customer reviews. Common themes in positive reviews include responsive customer service, billing accuracy, and the range of smart tariff options. Octopus has held Which? Recommended Provider status for multiple consecutive years.
Fuel mix
Octopus publishes an annual fuel mix disclosure confirming its electricity sourcing. The company states that electricity supplied to customers is backed by 100% renewable sources through REGO certificates and direct power purchase agreements with renewable generators. Check the Octopus Energy website for the current annual fuel mix disclosure.