Scotland secured a direct route to the USA, Canada, and Mexico by achieving a dramatic 4-2 victory over Denmark at Hampden Park.
Late goals from Kieran Tierney and Kenny McLean sealed the win, which Robertson described as "one of the greatest nights of my life".
Robertson shared that he and Jota, who passed away earlier this year, had often discussed their shared desire to play in a World Cup after both missed out on Qatar 2022.
He expressed that he couldn't get Jota out of his head on the day of the match and believed his friend would be "somewhere smiling over me tonight".