De Marco studied at St Aloysius' College and at Cambridge University, United Kingdom, where he graduated in international commercial law.

Following the March 2008 general election, he was appointed as member of the Cabinet, as Parliamentary Secretary for Tourism, within Prime Minister Lawrence Gonzi's office.

[1] In the March 2013 general election he was re-elected to parliament and was made the Nationalist deputy leader for parliamentary affairs in May that year.

He has acted as legal counsel to a major Italian communication company in a bid to enter into a strategic partnership agreement with the government of Malta for the design, development, implementation and operation of the e-Government services initiative.

He has also advised a number of blue chip companies in the telecommunication sectors and has represented international corporations in dispute resolution proceedings both locally and in London.