Bernal completed the 30.3-kilometer (18.8-mile) route in 35 minutes, 41 seconds to clinch overall victory by 1:29, the biggest margin of victory at the Giro since 2015
Giro d'Italia 2021: Britain's Simon Yates wins 19th stage, Egan Bernal stays strong atop leaderboard
Colombian Bernal, the 2019 Tour de France champion, finished third on the day to keep hold of the leaders' pink jersey with only two stages remaining.
Bettiol hunted down Frenchman Remi Cavagna of Deceuninck who had escaped from a big breakaway group with 26 kilometres to go and finished 15 seconds ahead of fellow Italian Simone Consonni.
Martin, 34, resisted his rivals superbly on the final climb, over 11.2km with an average gradient at 9.8 percent, after the 193km ride between Canazei and a summit finish at Sega di Ala in the north of Italy.
The Colombian star, who won the Tour de France in 2019, leads Italian Damiano Caruso by two minutes and 24 seconds with five stages of the Giro remaining.
Giro d'Italia 2021: Lorenzo Fortunato climbs to victory in 14th stage, Egan Bernal holds on to leader's jersey
Colombian Egan Bernal of Ineos was the first of the favourites to cross the finish line to consolidate his hold on the leader's pink jersey.
Egan Bernal of Ineos again held the leader's pink jersey before the feared Monte Zoncolan on Saturday.
Giro d'Italia: Andrea Vendrame sees off Chris Hamilton to take 12th stage, Egan Bernal retains overall lead
Vendrame finished ahead of Australia's Chris Hamilton, his final breakaway companion, followed by New Zealand's George Bennett and Italy's Gianluca Brambilla after the 212km run from Siena in Tuscany to Bagno di Romagna.
Team Qhubeka's Schmid won the 162km stage as part of a long-range breakaway while the 2019 Tour de France winner Bernal extended his overall lead in Tuscany.
Sagan's Bora-Hansgrohe team dominated the final 50km of the 140km race setting a sizzling pace to drop Sagan's rivals before the finale, where the 31-year-old cruised ahead of the reduced field for the win.
The Ineos leader and winner of the 2019 Tour de France pulled away from a select group on a gravel ski slope above the clouds with the other overall contenders only able to watch as he skipped away.
Giro d'Italia: Riders in peloton test negative for COVID-19, Tomasz Marczynski withdrawn after suffering symptoms
However one cyclist Tomasz Marczynski of the Belgian Lotto-Soudal team was withdrawn as a precaution because of symptoms related to the deadly virus ahead of the ninth stage.
Giro d'Italia: French cyclist Victor Lafay wins eighth stage, Attila Valter holds on to leader's pink jersey
Lafay, who rides for Cofidis, attacked on the steep uphill finish of the 170-kilometer (106-mile) leg from Foggia to Sanframondi and soloed to victory.
The 26-year-old Lotto Soudal leader won stage five earlier in the week and stage seven on Friday, and was leading the sprint points classification.
Hungary's Attila Valter of Groupama-FDJ held the leader's pink jersey after the 181km run between Notaresco and Termoli on the Adriatic coast.
Lotto rider Ewan overtook Giacomo Nizzolo to triumph in the final metres of a flat, initially uneventful stage that was suddenly hit by a raft of falls as the race came to its climax in Cattolica on the Adriatic coast.
Merlier, 28, riding for Alpecin, finished ahead of two Italians, European champion Giacomo Nizzolo and Elia Viviani, to claim his fourth win of the season.
World time-trial champion Ganna again pulled on the leader's pink jersey after finishing nearly 10 seconds faster than compatriot Edoardo Affini of Jumbo–Visma in the race against the clock.
Groenewegen has not raced since August 5 when he provoked a crash in the sprint at the end of the first stage in Poland that left fellow Dutch sprinter Jakobsen with injuries that included several skull fractures.
Matteo De Bonis tested positive for EPO in an out-of-competition control in March while teammate Matteo Spreafico fell foul of doping regulations twice on the Giro last October.