Cox's challenge involved covering 135 miles, equivalent to five marathons in five days, culminating in Pudsey, Leeds, on Friday.
Her journey began in Kielder Forest and traversed Northumberland, Durham, North Yorkshire, and West Yorkshire, with Cox carrying a distinctive Pudsey Bear backpack.
The Prince of Wales offered his congratulations for her remarkable effort, sending a video message played on Scott Mills' Radio 2 breakfast show.
The fundraising total, which surpassed £3 million on Thursday, prompted an emotional response from Cox, who thanked donors and highlighted the encouragement from women over 50.