Lloyds Bank Business says that, with over 5.5 million small ventures in the UK this could equate to more than 4.2million having no idea on how they will contribute to a more sustainable future.
Owners and managers said a lack of knowledge (34%), finance (25%) and time (25%) were the main blockers to having a defined sustainability strategy.
The bank's research also found that up to 2.5million business owners do not know what is meant by "net zero"'.
The definition of achieving a balance between the carbon emitted into the atmosphere and the carbon removed from it, was only known by half of respondents.
Just one in 10 of small firms know their carbon footprint, and only a sixth know how to calculate it.
Eight in 10 recognised the importance of being more sustainable, with 68% also aware that the UK Government has set targets to reach net zero.
The research also showed 40% do not think there is enough support available to realise these "green" ambitions. Younger business owners - those under the age of 35 - are most likely to be concerned about their carbon footprint (50%) and a third know how to calculate it.
Firms are also unconvinced that the UK Government's climate targets will make the country greener any time soon, with two-thirds doubting they will see a difference within their lifetime.
The bank says that the reservation that change will happen, alongside resistance in taking steps to make it happen, appear to be preventing business owners from shifting to a net-zero mindset.
Adam Rainey, commercial director of business banking at Lloyds Bank, said:
"While our nation's small businesses recognise the importance of tackling climate change, there are real issues with understanding how to get there - including calculating carbon emissions and even the meaning of net zero.
"Fortunately, there's a whole host of support available to help businesses make their first steps in becoming greener, from getting started with electric vehicles, practical guides to help reach net zero and tools to calculate potential energy savings at business premises.
We know it can seem daunting but some really simple things, such as reducing travel and recycling, are also great places to start."