Black Box Energy, in Little High Street, Worthing, has been awarded £45,000 from the Coast to Capital Business Growth Grant Scheme.
It will be used to set up a new customer support call centre and online facilities to better help customers with energy inquiries.
Managing director Matt Dowling said: “Since February, 2014, we have created six full-time employment opportunities in our company, as well as delivering a pipeline of work for local sub-contractors.
“We could not have done this without the support of Coast to Capital.”
The grants programme, managed by Coast to Capital, Brighton and Hove City Council and other commercial partners, helps local small and medium-sized enterprises expand their businesses by supporting projects including skills improvement, research and development and investment in equipment or premises.
The latest round of grants have seen 120 jobs created across the region.
Worthing Borough Council cabinet member for regeneration Bryan Turner said: “I am absolutely clear that the council needs to be doing everything it can to connect companies such as Black Box Energy with the sources of growth capital they need to expand.
“Worthing is a place for innovative, creative companies such as Black Box Energy - and I look forward to hearing more about their expansion in the very near future.”
Coast to Capital chief executive Ron Crank said the latest round of grants showed how significant a role such businesses played in the local economy.
He said: “These businesses are the drivers of our regional economy, so we are pleased to be able to support them and I encourage others in a similar situation to get in touch with my team at Coast to Capital to see if we are able to help their growth plans.”
A new round of funding may become available early in 2015. For more information, visit www.coast2capital.org.uk/helping-business-growthional-growth-fund