The Pharaohs headed into a meeting with Congo knowing that victory would see them progress as winners of their qualification group.
They were, however, made to sweat on their place in Russia until the dying stages of a crunch clash.
Everything looked to be going to plan when Salah opened the scoring just past the hour mark, but a dramatic stoppage-time penalty was required to get the job done.
A stalemate would have taken the battle for qualification down to the final round of fixtures.
There was, however, to be a late twist in the tale.
Egypt were awarded a 95th-minute spot-kick, and Salah held his nerve to find the back of the net and wrap up a historic win.
He will now be gracing the grandest of stages next summer alongside his international colleagues and many of his Liverpool team-mates.
They have never won a game at that level, so there is the chance for history to be made in 2018.
Salah will be hoping to play a leading role in that quest, with the 25-year-old proving to be a talismanic figure for his country.
His brace against Congo means that Liverpool’s €42 million summer signing is now the leading scorer in the CAF section of qualifying with five goals.
Egypt, who now boast a four-point lead over Uganda, will face Ghana in their final fixture on November 6.