The 85-year-old was hit by a Nissan van in Vectis Way, Cosham, near its junction with the high street at around midday today.
Hampshire police have arrested a 61-year-old man from Cosham on suspicion of causing death by careless driving.
A spokesman said the woman’s family are being supported by specialist officers.
He said: ‘Officers investigating the exact circumstances of the collision are keen to speak with any witnesses or anyone who has dash cam footage.
‘If you can assist, please call 101, quoting the reference number 802 of today's date (October 7).
‘The road was closed while we attended, but this has now been reopened.’