The burgeoning talent at Southgate's disposal was on show as 18-year-old's Jadon Sancho and Callum Hudson-Odoi also played their part in a perfect start to England's Euro 2020 qualifying campaign.
Sterling, 24, was often criticised as he scored just two goals in his first 45 caps. But the Manchester City winger now has five in his last three England games after also scoring twice in a famous 3-2 Nations League win in Spain in November.
"I thought he was devastating tonight," said Southgate.
"I'm delighted for him to get the reaction that he did from the crowd here. We can't hide from the fact that he's had difficult moments with England and he's turned that full circle," said Southgate.
"I also think the goals in Spain were an important moment for him; you could see the release that had brought.
"His finishes there and tonight were finishes that he was just taking on without thinking too much. At times, you could almost see the thought process in the past, but he's hungry for those goals."
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Harry Kane was also on target from the penalty spot and Tomas Kalas's calamitous own goal rounded off the scoring as England carried on their momentum from a run to the World Cup semi-finals and qualification for the last four of the Nations League.
The final of Euro 2020 will be played at Wembley and England have high hopes of being more than just hosts, especially with Sancho and Hudson-Odoi to add to an already talented front line boasting Sterling, Kane and Marcus Rashford.
Southgate admitted even more improvement is to come as his side ran out comprehensive winners despite a lacklustre start.
But one move of genuine quality opened the floodgates on 23 minutes.
Kane showed his ability is not restricted to finding the net with a wonderful pass inside Filip Novak to free Sancho, who squared for Sterling to tap home on the stretch.
Another burst of inspiration from Sterling helped double England's lead in first-half stoppage time.
He wriggled around four Czech defenders before a combination of Pavel Kaderabek and Tomas Kalas hauled him down.
Kane maintained his flawless record from the spot for England and scored his 21st international goal, firing his powerful penalty past Jiri Pavlenka despite the Czech stopper getting a hand to it.
England went through the gears after the hour mark and Sancho should have scored his first international goal after more good work from Sterling and Kane, but could not force the ball past a desperate challenge from Novak.
Sterling soon showed Sancho how it is done with a fine curling finish into the top corner.
However, England's hat-trick hero had luck on his side for his third goal as a huge deflection left Pavlenka in the Czech goal flummoxed.
That was Sterling's final act as he made way for Hudson-Odoi, to make his international debut, while Declan Rice was also handed his England debut after switching allegiances from the Republic of Ireland.
And Southgate believes Sterling's experience of the highs and lows of being an England protégé makes him the perfect role model for the likes of Sancho, Hudson-Odoi and Rice.
"I've put him into the leadership group that we have. I think he's showing those signs, I think he's a role model for the younger players coming in," added Southgate.
"I think he's enjoyed that extra responsibility as well.
"That shone through on the pitch, so a really special night for him."
Hudson-Odoi had a big part to play in England's fifth as his shot was parried by Pavlenka into the onrushing Kalas, who haplessly turned the ball into his own net.
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