Penelope Warne, senior partner of CMS, believes pooling the skills of the two firms in areas like financial services and energy will help the enlarged business win more work in some lucrative markets in Scotland.
She said the former Dundas and Wilson operations in Scotland could also expect to win plenty of work outside the country, including referrals from CMS' operations around the world.
She said: "They're going to come to really high quality corporate and banking lawyers in Edinburgh and Glasgow before they go to more expensive lawyers in London for some of their back up services."
Ms Warne also highlighted the potential for the Glasgow-based legal services unit to win more transaction support work from London.
Caryn Penley, the former joint managing partner of Dundas and Wilson, who has joined the CMS board, said: "Our client base is partly based in Scotland but we also have a number of quite large clients who are internationally based and they want legal firms who can provide services right across the globe and in quite specialist areas of expertise we could not provide on our own."
Ms Penley said the consolidation process would continue in the legal market, but there would always be a place for "specifically Scottish firms".
Law firms found revenue came under pressure amid the economic downturn.
Dundas and Wilson made 40 support staff redundant ahead of the merger completing, while 20 jobs were shed at CMS and its outsourcing suppliers .
Ms Penley added that three partners in Dundas and Wilson had made the decision "not to make the jouney" into CMS, including former chairman David Hardie.
Some 69 former Dundas and Wilson partners have become partners in CMS.
It has 212 partners in the UK and 618 in other countries.
Ms Warne said the chance of Scotland voting for independence in September had not affected her enthusiasm for the merger.