While Rawat won Dharchula seat by over 20,000 votes, Congress's Hira Singh Bisht won from Doiwala by over 6000 votes whereas Congress' Rekha Arya won Someshwar (reserved) seat by over 9000 votes, Uttarakhand's Chief Election Officer Radha Raturi said.
Rawat got 31214 votes against his nearest rival BJP's BD Joshi who garnered 10610 in Dharchula.
In Doiwala, Hira Singh Bisht of the Congress polled 35980 votes against BJP's Trivendra Singh Rawat who got 29465 votes.
Congress' Rekha Arya bagged 22996 votes in Someshwar against BJP's Mohan Ram Arya who got 13091 votes, she said.
Bypoll to these seats was held on July 21 after Dharchula was vacated by Congress MLA Harish Dhami for the chief minister to help him fulfil the constitutional requirement of entering the state assembly as an MLA. Doiwala and Someshwar seats fell vacant after their sitting MLAs Ramesh Pokhariyal Nishank and Ajay Tamta respectively were elected to the Lok Sabha.
Congress' bypoll victory in Uttarakhand is a shot in the arm for the party which had lost all five seats to the BJP in the Lok Sabha polls.
Further consolidating the party's position in the state assembly, victory in these seats helps the Congress reach the half-way mark on its own in the 70-member House by raising the number of party MLAs from 32 to 35.
The party had failed to muster a majority in the 2012 assembly elections and existed on the prop of the seven-member PDF, a front consisting of BSP, UKD and Independent MLAs.
Elated at its bypoll performancewhich comes after the Lok Sabha poll rout at the hands of BJP which was riding high on a Modi wave, Congress leaders here said it was an indication that the "so-called Modi wave is on the ebb".
"Uttarakhand bypoll results, which have been overwhelmingly in favour of the Congress, show that the Modi magic has begun to fade," PCC spokesman Dhirendra Pratap claimed.
Soon after the party's triumph, Rawatwho had sought votes on the plank of stability, thanked the people of the state and promised to meet their expectations.
Another significant victory was recorded by Congress in the high-profile Doiwala seat which traditionally belonged to the BJP and was held by former chief minister Ramesh Pokhariyal Nishank.
With Congress's Hira Singh Bisht winning the Doiwala seat, the party has penetrated a BJP citadel winning the seat for the first time in 20 years.
The bypoll outcome deals a blow to BJP in the state reducing the number of its MLAs in the state assembly from 30 to 28.