The supplier - owned by Nottingham City Council - doesn't disclose how many customers it has, but those on its standard Evergreen tariff will see bills rise from 22 April.
The increase will mean a typical user on the Evergreen tariff, paying by monthly direct debit, will pay an extra £150/year on average, with their average annual bill rising to £1,057/yr.
Robin Hood Energy's announcement follows a spate of price hikes across the energy market in recent months. If you're one of 66% still on your suppliers standard tariff, it's likely you're overpaying - so check now to see if you can lock in to a cheap deal via our Cheap Energy Club.
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Customers with white label providers will also see bills rise
Robin Hood Energy's price hike won't just affect its own direct customers. Anyone on a standard tariff with The Energy Deal, Brighter World Energy and White Rose Energy will also see bills rise, as Robin Hood is the supply partner for these providers.
If you're with The Energy Deal, your bills are set to rise the same as Robin Hood Energy customers, while the hike may vary with new provider Brighter World Energy and White Rose Energy, which only supplies gas and electricity in the Yorkshire region.
However customers of the prepay energy supplier Ebico, which recently announced a new partnership with Robin Hood Energy, WON'T be affected for the time being, as both suppliers have agreed a price guarantee until at least December 2017.
'Rise in wholesale energy costs' to blame
In a statement on its website, Robin Hood Energy said: "Since its launch in September 2015, Robin Hood Energy has kept its prices as low as possible to support our customers. However a rise in wholesale energy costs has made purchasing gas and electricity more expensive.
"Since 2016 the price of wholesale energy purchase has gone up significantly and this affects our ability to keep prices as low as we'd like them to be. The price increases…have been kept as low as possible to minimise the impact they have on our customers."