He will replace Sir Paul Girolami, Glaxo's well-known chairman, who is stepping down from the committee.
Despite being chief executive of Glaxo for four years, Ernest Mario, Sir Richard's predecessor who left last year after a clash with Sir Paul over the company's direction, was never chairman of the executive committee.
The committee is also being strengthened through the addition of two more senior executives: Goran Ando, director of development and product strategy, and Sir Mark Richmond, head of research.
Glaxo, which is expected to announce pre-tax profits of about pounds 950m in its interim figures released tomorrow, is also shaking up its American management. Charles Sanders, chairman and chief executive of Glaxo Inc, Glaxo's US subsidiary, is retiring at the end of February. He will be succeeded by Robert Ingram, who is currently Glaxo Inc's president.
However Dr Sanders, who is 62, will remain on the main Glaxo board as a non-executive director and will continue to represent the company in the key current round of US healthcare reform.
The company also said that Arthur Pappas, the director responsible for Canada and Latin America, had left. It gave no reason.
Also retiring from the main Glaxo board is John Hignett, in charge of the management and investment of corporate funds. John Coombe, the finance director, will take over.
Shares in Glaxo, which have been heavily sold along with other big drug stocks, strengthened in anticipation of a good set of results.
'They have nowhere to go but up,' said one analyst.
The shares rose to close up 10p at 675p.