Trippier's free-kick was not only his maiden England goal but was his first goal of any kind since he scored for Tottenham against Watford on February 6, 2016 - 886 days ago.
England will play France if they reach the final and World Cup-winning goalkeeper Gordon Banks was in confident mood about the team's chances of victory.
The biggest winners of the night could well be France, who have had an extra day's rest for Sunday's final after edging out Belgium 1-0 on Tuesday.
"We have shown that we can win knock-out games and get to semi-finals, so now we have to try and go one step further".
Croatia have been taken to penalties twice in the knockout stages and again had to endure extra time against England.
Who will advance to the World Cup final Croatia or England? They were down against Denmark in the round of 16 and advanced.
England face Croatia in the World Cup semi-finals on Wednesday.
Southgate stuck with the same starting line-up as that which eased past Sweden in the quarter-finals, while Inter Milan's Marcelo Brozovic replaced Andrej Kramaric in the Croatian line-up.
England played six games on that occasion, the same as Southgate's men who still have the third-place play-off to add to their tally.
Another alternative to watch the Croatia vs England World Cup game online without cable is via Hulu Live TV with complete World Cup coverage.
Tottenham's Dele Alli admits discontent over World Cup form with England
We want to get close to them, although it is hard to repeat this endeavour, but we will try", the 51-year-old told reporters. On Wednesday, his team has a chance to write a new page in Croatia's football history.
Croatia coach Zlatko Dalic made one change from the side which beat Russian Federation on Saturday with Marcelo Brozovic coming in for Andrej Kramaric.Croatia got off to the worst possible start when in just the 5th minute Kieran Trippier curled in a free kick to the top right corner from just outside the box to give England a 1-0 lead.
In Moscow, Croatia fans said they were taken aback by their side's win.
"Croatia were better than them".
Croatia was one of the most impressive teams of the group stage before surviving two penalty shootouts to reach this point. Suddenly, England was rattled and Croatia was resurgent.
Croatia's Mario Mandzukic scores the decisive goal in his team's semifinal against England.
Vrsaljko cleared a John Stones header off the line midway through the first extra period.
It was a wonder the Juventus forward did not break a limb as Pickford crunched into him.
England had its moments to come back but could not finish its chances. They brought two Israeli cancer patients with them, 18-year-old Mika Lipsker and 13-year-old Alon Izraev.
They had won just one knockout match at a major tournament in 16 years before coming to Russian Federation, a 1-0 victory against Ecuador at the 2006 World Cup in Germany.
This Croatia team doesn't know how to quit.
Croatia is showing the world that their 1998 golden generation - a side that also went to the World Cup semifinal - was not an aberration and that the country can produce top-level soccer talent to compete with the world's best.