Four people lost their lives when terrorist Khalid Masood mowed down pedestrians on Westminster Bridge before stabbing PC Keith Palmer outside the Palace of Westminster.
Tributes have poured in from across the country and England will offer their recognition with a minute’s silence before kick-off at a sold-out Wembley Stadium, as was observed in domestic games in the EFL on Saturday. The Three Lions players are also expected to wear black armbands.
In November 2015 England hosted France in a Wembley friendly just days after the attacks on Paris that left 130 dead with the national stadium providing an impeccable tribute to their visitors on an emotional night.
Southgate said: “We know how important the national football team is for the feeling of the nation and it’s a great opportunity for everybody to show their respect at that moment and show that, as a country, we go on. Not only London but the country as a whole.
“I thought the tribute before the France game was really poignant and I’m sure tomorrow will be the same.”
Southampton full-back Ryan Bertrand, who grew up in Southwark, added: “We were away at the time but I managed to see through social media how strong we were as a country and as a city.
"The whole of London was coming together.”
The Football Association have put together a “robust” security plan in light of Wednesday’s attack on Westminster.
In the hours after the attack England were playing in Dortmund, losing 1-0 to Germany through a Lukas Podolski strike on the former Arsenal forward’s final international appearance.
However the evening was marred by vile chants from a section of the travelling supporters, who made several references to the First and Second World War.
The England Supporters Travel Club is to withdraw the membership of any fans involved in anti-social, xenophobic or disrespectful behaviour on Wednesday and Southgate urged fans to remember that they represent their country when travelling abroad.
“Tomorrow it’s important that [the situation] is respected in the way it was before the France game,” he said. "That was a great advert for England supporters and for England as a nation.
“The supporters are no different to the team: they represent the country when they go away. We want to be good ambassadors and set a good example.
“The majority of our supporters do that. I have to say in general our support is excellent, we have some who unfortunately who were chanting things the other night that were unacceptable.
“We would prefer to focus on those that support us well and get behind the team. We’ve got a sell-out crowd tomorrow and we’re grateful for their support.”