The commodity-heavy FTSE 100 index ended 1.6% higher, with energy and mining heavyweights BP and Rio Tinto supporting the index on the back of strong oil and base metal prices.
The domestically focused mid-cap FTSE 250 index added 1.1%, ending at its highest level since early-March with industrial stocks serving as the biggest boost.
Both indexes surged in late trade, tracking gains on Wall Street after the formal go-ahead for President-elect Joe Biden's transition to the White House ended weeks of political uncertainty in Washington.
Travel stocks rallied after England said it would introduce a new COVID-19 "test-and-release" scheme on Dec. 15 to reduce quarantine periods for incoming passengers from high-risk countries.
"Investors are still thinking long-term post-vaccine at the moment and are looking into various sectors that have been haemorrhaged in the last eight months," said Connor Campbell, financial analyst at Spreadex.
A sharp rally in cyclicals such as energy and bank stocks on vaccine-related cheer and hopes of a speedy economic recovery have helped the FTSE 100 index gain more than 14% this month, setting it on track for its best month on record.
Among individual movers, Catering firm Compass Group Plc rose 2.5% even as it reported a 75.5% slump in annual pretax profit.
Online electricals retailer AO World sank nearly 10% after it said it doubled its warehouse capacity to cope with any possible supply disruptions caused by Brexit.
(Reporting by Devik Jain in Bengaluru; Editing by Uttaresh.V and Alex Richardson)
By Devik Jain and Ambar Warrick