Stuart Young is the new Minister of Energy.
He will replace Franklin Khan, who died suddenly on Saturday morning.
A release from the Office of the Prime Minister (OPM) said Dr Rowley had advised the President that, with immediate effect, Young would be moved from the National Security Ministry.
He will retain his portfolio as a minister in the OPM.
“I thank the Prime Minister, Dr the Honourable Keith Rowley, for his confidence in me in his reassignment of me to the portfolio of Minister of Energy and Energy Industries, in addition to my duties as Minister in the Office of the Prime Minister,” Young said in a Facebook post.