• The leaders are meeting in the city for an annual security conference, but with Russia absent this year.
• Western allies have warned Russia could invade Ukraine imminently, with over 130,000 of its troops near the border.
Boris Johnson has urged other Western leaders to show unity ahead of talks about the crisis in Ukraine.
Ahead of travelling to Germany, where he will give a speech in Munich later, he said an "overwhelming display of Western solidarity" was required.
The leaders are meeting in the city for an annual security conference, but with Russia absent this year.
Western allies have warned Russia could invade Ukraine imminently, with over 130,000 of its troops near the border.
US President Joe Biden said he is convinced Russian President Vladimir Putin has decided to invade and that an assault could happen in the "coming days".
Mr Biden said the assessment was based on US intelligence, which suggested the capital Kyiv would be targeted.
But Russia has repeatedly denied any invasion plans, accusing the West of "hysteria".
Moscow said it was conducting military drills and that some troops had been moved back to their permanent bases in recent days.
But Western powers said they had seen no evidence of withdrawal - with US officials increasing their estimate of Russian troop numbers on Friday.
Mr Johnson travelled to the Bavarian capital on Saturday to join other leaders in speaking at this year's Munich Security Conference.
Other Western politicians taking part in the three-day event include German Chancellor Olaf Scholz and US Vice-President Kamala Harris.
Downing Street said Mr Johnson would discuss the Western response with a number of European partners.
But Russia will not be officially represented at the summit for the first time since 1999 amid the rising tensions over the situation at Ukraine's borders.
Ahead of travelling to Germany, Mr Johnson said that "diplomacy can still prevail" in averting conflict.
"There is still a chance to avoid unnecessary bloodshed, but it will require an overwhelming display of western solidarity beyond anything we have seen in recent history," he added.
The PM said allies needed to speak to Russian President Vladimir Putin "with one voice" to stress "the high price he will pay for any further Russian invasion of Ukraine".
Mr Johnson had previously said Western countries had prepared a "very tough" set of sanctions to impose on Russia if it invaded Ukraine.
The government also announced new legislation allowing the UK to widen its own sanctions against the country.
In addition, the Home Office has scrapped a visa scheme offering rich foreign investors fast-track residency, amid pressure on ministers over UK links to Russia.
Labour has demanded the immediate publication of an ongoing review into visas granted between 2008 - when the scheme was introduced - and 2015 when checks on applicants were tightened.
The Liberal Democrats have also demanded a "clear timetable" for revoking visas issued to any Russians "who have been flagged as posing a national security risk".
The security conference in Germany comes as Ukrainian forces and Russia-backed rebels in the country's east continued to accuse each other of shelling and other ceasefire violations on Friday.
Such breaks in the area's years-long ceasefire are not uncommon, and each side blamed the other for the violence on Thursday.
On Friday, Washington increased its estimate of the number of Russian troops deployed around Ukraine to between 169,000 and 190,000.
Ukraine's defence minister has suggested a figure of 149,000.
US President Joe Biden has warned that Russia is trying to engineer a pretext to invade Ukraine.
But Moscow called the claims "baseless" and accused Washington of ignoring its security demands and threatening "military-technical measures".