That will see it continue to provide mentoring, bootcamp sessions and legal clinics in areas including intellectual property, employing and franchising to entrepreneurs in Glasgow, Edinburgh and Ayrshire.
Harper Macleod will also be involved in E-Spark's new nest concept for companies which are beyond the start-up stage.
Paula Skinner, partner, said: "We have enjoyed working with E-Spark, helping businesses come through the Hatcheries and seeing them progress."
Jim Duffy, co-founder of E-Spark, said: "We are delighted to continue our association with Harper Macleod, who have fully bought in to what we are trying to achieve.
"Like us, they recognise that a new generation of entrepreneurial businesses is vital to the wellbeing of Scotland's economy and will pay dividends for the entire business community."
Separately, Harper Macleod said it has been appointed to the Highland Council Legal Services Framework Agreement.
That covers work in Highland Council, Shetland Islands Council, Orkney Islands Council and Comhairle nan Eilean Siar until November 2016 and there is an option to extend it for a further 12 months.
Harper Macleod said the work could be worth up to £4.27 million and that it was the top ranked firm in the 16 lots it tendered for.
Areas covered include employment, commercial contracts, finance, property and freedom of information.
Lorne Crerar, chairman of Harper Macleod, said The Highlands and Islands are an important part of the firm's growth strategy and added: "We are absolutely delighted to be appointed to the framework to provide services to the four local authorities in all these areas of work."
There were 18 lots up for grabs in the framework and 14 firms have been appointed to the various panels.