PORTUGAL 2 Aug 2015, (AFP) - The 33-year-old finished three clear of Scotland's Scott Henry thanks to the best final round by a European Tour winner this season.
It also helped him to set a new record for the lowest winning score in the tournament's 22-year history at 24 under par.
Britain's Andrew McArthur finished in third, six shots off the lead, with Swedish duo Pontus Widegren and Sebastian Soderberg a further two shots back.
Mikko Ilonen is the only other Finnish player to have won on the European Tour with five titles to his name.
"This is definitely the best moment of my career but I have to say that it really helped me to have won two years ago on the Challenge Tour in Oman," said Kakko.
"I was at a stage where I really needed to win and I did it, and that really helped me today, calmed me down when the pressure was on."
Leading fourth round scores and totals in the Madeira Islands Open at Santo da Serra, Madeira, Portugal on Sunday (GBR & IRL unless stated, par 72):
264 - Roope Kakko (FIN) 66 71 64 63
267 - Scott Henry 66 70 65 66
270 - Andrew McArthur 68 70 69 63
272 - Pontus Widegren (SWE) 67 66 67 72, Sebastian Soderberg (SWE) 67 74 66 65
273 - Tom Murray 70 68 68 67
274 - Bjorn Akesson (SWE) 71 65 68 70, Brandon Stone (RSA) 68 68 66 72, Callum Shinkwin 68 70 70 66
275 - Tiago Cruz (POR) 73 69 65 68, Fredrik Andersson Hed (NED) 72 69 68 66, Ryan Fox (NZL) 65 73 72 65
276 - Jose-Filipe Lima (POR) 70 68 69 69, Ricardo Santos (POR) 66 76 69 65, Pierre Relecom (BEL) 68 68 70 70
277 - Rhys Davies 67 71 67 72, Christopher Mivis (BEL) 70 69 69 69
278 - Carlos Del Moral (ESP) 69 70 68 71, George Murray 69 71 69 69, Alessandro Tadini (ITA) 68 71 70 69, Andreas Harto (DEN) 66 74 67 71, Chris Paisley 66 72 70 70, Adrian Otaegui (ESP) 70 71 68 69, Nacho Elvira (ESP) 64 74 72 68
279 - Nico Geyger (CHI) 69 72 69 69, Jean-Baptiste Gonnet (FRA) 69 69 72 69, Ricardo Gouveia (POR) 68 72 71 68, Antonio Hortal (ESP) 63 71 72 73, Pedro Oriol (ESP) 66 71 74 68 280 Tjaart Van Der Walt (RSA) 70 72 70 68, Sam Walker 67 66 73 74