The 88-year-old Ahmed featured in Pakistan's first Test played in Delhi against India in October 1952 and went on to play 41 matches as a wicketkeeper-batsman.
Ahmed's family confirmed his death.
"He (Imtiaz) was suffering from chest infection and died early Saturday," a member of the family told local media.
Ahmed was known as an aggressive batsman who had a variety of strokes, most notably the hook and the pull shot. He scored 2,079 Test runs for Pakistan with a career best of 209 against New Zealand in Lahore in 1955.
Mohammad, who died in August this year, went on to score an epic 337 in 970 minutes -- still the longest innings in Test cricket history.
Ahmed's death means that middle-order batsman Waqar Hasan is now the only surviving member of Pakistan's first Test team.