Muir took 1500m glory in a race befitting her domination in the field, leading from start to finish to run a Championship record of 4:02.39 to win by a comfortable margin, picking up her very first European Indoor medal.
As if it wasn't enough to beat that time which had stood for 32 years, Muir will also leave Belgrade with the British record, narrowly beating Dame Kelly Holmes' time that had stood for more than a decade.
It's an honour that comes barely a fortnight since taking the 1000m title from Holmes too, with the 23-year-old at a loss to explain just how she was able to take top honours, something that has alluded her through her career.
"I'm just so happy, it feels like a long time coming to win a medal," she said.
"I knew a couple of the girls would have a good sprint finish so I played to my strengths to take it out and hold on.
Muir smashes championship and British record in 1500m win in Belgrade
"I just wanted to run a quick race, but I never envisaged to run that fast so it's absolutely brilliant.
"I'm still only 23 so I've got a few more years yet, but in the last couple of years the medals have slipped away so I'm relieved to be able to get that."
Kilty defends sprint title with stunning run
The 23-year-old Muir already holds three European records.
Muir won by over two seconds ahead of the 3,000m final on Sunday.
European Indoor Women's 1500m final times
1. Laura Muir (Britain) 4:02.39
2. Konstanze Klosterhalfen (Germany) 4:04.45
3. Sofia Ennaoui (Poland) 4:06.59
4. Meraf Bahta (Sweden) 4:07.90
5. Luiza Gega (Albania) 4:11.64
6. Sarah McDonald (Britain) 4:13.67
7. Darya Barysevich (Belarus) 4:13.81
8. Amela Terzic (Serbia) 4:25.15
. Ciara Mageean (Ireland) DNF
Richard Kilty defended his title in 6.54secs after British team-mate Andy Robertson was disqualified for a false start in the final.
"When it really matters I'm willing to lay my heart on the line and put in my best performance," said Kilty.
Richard Kilty of Britain celebrates winning.
Image credit: Eurosport
That was not the only success in the women's 1500m, with Sarah McDonald leaving absolutely everything out on the track to finish in a time of 4:13.67 and take fifth place. Germany's Konstanze Klosterhalfen took silver, while Poland's Sofia Ennaoui finished third.
But there was still more to come from the British stars in Serbia, with Kilty defending the 60m title he picked up just 12 months ago.
The 27-year-old held his nerve after a disrupted start to cross the line in 6.54 seconds, showing the exact form that had seen him dominate in the heats.
Theo Etienne took a valiant fifth place in his first race at senior level, stopping the clock at 6.67s, while Andy Robertson was set to be a third British competitor in the final, only to be disqualified for a false start to end his medal chances.
"It's absolutely amazing to defend my title," said Kilty. "I don't know what to say, there have been so many emotions in the last few weeks and my has changed around now.
"I've just come here and defended my title and never been defeated in a European Championships, it feels awesome.
"I'm a great believer that adversity makes you stronger, and I've been through a fair few things of adversity, but when it really matters I'm always willing to put my heart on the line and give a performance."
European Indoor Men's 60m final times
1. Richard Kilty (Britain) 6.54
2. Jan Volko (Slovakia) 6.58
3. Austin Hamilton (Sweden) 6.63
4. O'Dain Rose (Sweden) 6.63
5. Theo Etienne (Britain) 6.67
6. Pascal Mancini (Switzerland) 6.70
7. Sulayman Bah (Sweden) 6.96
. Andy Robertson (Britain) DSQ
There was heartbreak for 400m runner Laviai Nielsen though, overtaken on the line as she was forced to settle for fourth place in Belgrade.
The 20-year-old was pipped to the post by Poland's Justyna Swiety who grabbed the bronze medal, with France's Floria Guei winning gold and Czech Zuzana Hewjonova the silver.
But Nielsen, whose twin sister Lina was forced out of the competition with a leg injury, is still in with a chance of topping the podium when she runs in Sunday's 4x400m relay final.
From track to field, and Lorraine Ugen wasted little time in reaching the long jump final – jumping a season's best 6.80m from her very first attempt – while Jazmin Sawyers finished with a jump of 6.54 to also make the medal competition.
Sunday's action will also see Robbie Grabarz and Allan Smith take to the high jump final, though Chris Kandu missed out having finished tenth in qualifying.
Asha Philip will be eyeing up a medal on the third day of competition, qualifying fifth fastest for the 60m semi-finals, winning her heat in 7.25s.