Chelsea Addison, of Walsall, and Steven Dema, both aged 30, "craved the cash rich lifestyle which comes with serious crime", a judge said as he sentenced them to more than 11 years each in prison.
Addison paid Dema to travel to Amsterdam to collect a Zastava assault rifle, a Zoraki 9mm pistol and more than 100 rounds of ammunition.
The guns and ammunition, as well as £4,500 in cash, were recovered when Dema was stopped in a hired Mercedes sports car by Border Force officials at the Channel Tunnel terminal near Calais in March.
National Crime Agency officers believe the duo had already successfully imported firearms for UK-based criminals.
Investigators established that Addison had organised the same trip for Dema on three previous occasions, and the pair were using an encrypted messaging phone app called Wickr in order to conceal their criminal activities.
When questioned Dema claimed he worked as a personal trainer and a bodyguard, and Addison said she was a dancer.
But both had taken lavish city breaks to Europe together, and had discussed flying business class to Jamaica and the Maldives, as well as potential holidays to the Cayman Islands and Italy.
When questioned, Dema, who claimed he worked as a personal trainer and a bodyguard, told officers he was involved with a dancer called Chelsea Addison who he hadn’t treated very well, the NCA said.
He said that in retaliation for his behaviour she had organised for gang members to threaten him, and he had been forced to travel to Amsterdam to collect a suitcase from a car park.
Dema maintained that he did not look inside the suitcase and was going to take it straight to Addison, with whom he was in constant communication during the trip as she was checking on his whereabouts.
Meanwhile Addison, who was arrested at her Walsall home in April, said she worked as a dancer and claimed that Dema sometimes took her phone for days on end and was making false claims to make her the scapegoat for his criminal activities.
However DNA from the suitcase and its contents, analysis of phone data, and evidence of the trips to Amsterdam proved their stories were false and they had well-established roles in the importation of firearms.
The Zastava M70AB2 gun collected in Amsterdam is a variant of the Soviet Kalashnikov AKM rifle made in the former Yugoslavia, while the Turkish Zoraki hand gun was originally made to fire blanks but had been converted to fire live ammunition.
Addison, of Alderley Crescent in Walsall, was jailed for 11 years and six months, while Dema, who lived in Blackpool, was sentenced to 11 years and nine months on Wednesday.
Addison admitted two counts of fraudulent evasion of a prohibition (firearms importation) while Dema was found guilty of the same charges after a trial.
Dema also pleaded guilty to possessing cannabis and a false identity document.
Martin Grace, Branch Commander at the NCA, said: "This was an attempt to import two lethal guns and enough live ammunition to cause untold damage if used on the streets.
“Illegal firearms are used by organised crime groups to dominate and intimidate communities, to enforce control over criminal markets like the class A drugs trade, and they ruin lives when used to cause death and serious injury.
“Stopping the supply of firearms is a priority for the NCA. Our investigation is not over and we will do everything we can to pursue those involved.”
Sentencing, Judge James, at Canterbury Crown Court said: “Both of you seem to have been seduced into criminal activity by greed.
"It is apparent that you both craved the cash rich lifestyle which often accompanies serious crime.”