The 40-year-old presenter was speaking about the best inventions that would be discussed on the programme throughout the week.
However, Alex ended rubbing up the wrong way her nature-loving friend Matt, 39, after saying that without concrete there would be no homes.
Introducing the show, Alex said: “Tonight we are firing the starting gun on the hunt for the UK’s greatest ever invention. The mobile phone, the jet engine. Even, get this, concrete.”
As laughter filled the studio, Matt said: “Yes, well television is one of the seven brilliant innovations as well that will be championed on the show all this week, and without television, tonight’s guests might find themselves in a spot of trouble, as would we.
“So also on this list we’ve got steam engines, antibiotics, fridges…,” as Alex continued: “Without concrete, no homes.”
Puzzled, Matt grinned at his co-host and said: “Well, to be fair, there are a lot of homes that aren’t built with concrete.”
Pausing, Alex mocked Matt’s other presenting job and replied: “Alright Countryfile!”
In hysterics, Matt quickly snapped back: “No, it’s just general building knowledge!”
One viewer tweeted: “I did an actual out loud laugh at Alex’s comeback ‘alright Countryfile’ to Matt! @BBCCountryfile @BBCTheOneShow.”
“‘Alright Countryfile’ is deffo line of the day, love it @MissAlexjones @BBCTheOneShow,” posted another, as a third wrote: “What a shout that was from @MissAlexjones ‘Alright Countryfile’.”
A fourth posted: “‘Alright Countryfile’ best line ever from @MissAlexjones on @BBCTheOneShow,” as another said: “‘Alright, Countryfile!’ – @MissAlexjones You legend #TheOneShow.”
The One Show continues tomorrow on BBC One at 7pm.