The Quick-Step sprinter made powerful progress on the uphill finish to the 195km event, edging out Stefan Van Dijk of the Netherlands and Australia's Graeme Brown in the race to the line.
The veteran had been without a win since the 2009 Ruta del Sol, but got everything right on the cobble-stone finish.
“I'm thrilled” said Steegmans “The team worked really well. In the last 400 metres everything just clicked; it wasn't a chaotic sprint, but quite orderly, just like I like it, with ideal conditions for me to progressively unload my power on the pedals.
"I feel in great shape and I hope to continue like this for the next steps of the season."