The 27-year-old Ramkumar, who had lost six Challenger finals in his career before, beat his Russian rival 6-1 6-4 in 68 minutes.
Ramkumar, seeded sixth and ranked 222 in the world, sealed the first set when the Russian's backhand return sailed over the baseline.
This was after Ramkumar saved a breakpoint against Karlovskiy, ranked 302 in the world. That was the only time he faced a break point in the contest.
The Indian served extremely well and his net game too was sharp.The 80 ranking points earned will push Ramkumar back into top-200 and also make him the highest-ranked Indian on the ATP singles ranking chart.
He is likely to be ranked 186 and will surpass Prajnesh Gunneswaran (215) and out-of-action Sumit Nagal (219) when the chart is updated.
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