The 24-year-old, ranked world No. 4 by the Women's Tennis Association (WTA), saw off Ukrainian qualifier Daria Snigur 6-1, 6-2 in their second-round encounter on Thursday.
The Polish player, who had a bye in the first round, will now face American Ann Li at the clay-court tournament in the Spanish capital.
Świątek reached the semifinals in Madrid last year after winning the title in 2024.
The 2026 Madrid Open runs until May 3.
(gs)
Source: IAR, PAP