The former BP 2go petrol station on the corner of Jones Street and Anzac Parade is undergoing a facelift.
Mobil is set to take over the site and will open in mid-July following the completion of upgrades at the site.
New owner Onil Gulati is in charge of several other Mobil-branded sites, in Morrinsville, Wairoa, Te Rapa and Frankton.
He is also developing stations in Whakatane and Kumeu.
Gulati said he was proud to bring Mobil back to Whanganui.
The convenience offering would undergo "a complete renovation".
"The results will speak for themselves."
Mobil lead country manager Andrew McNaught said Gulati's investment in the site recognised Whanganui's importance as a growing commercial centre in the North Island.
"As Whanganui and its surrounding district continue to grow, Mobil Whanganui will play an integral part in servicing the community."