It's the Spaniard's ninth career stage win at his home Grand Tour, but he didn't even have enough time to celebrate with his arms in the air as a reduced lead group raced right to the finish line in Vejer de la Frontera.
On a relatively flat day, the steep, uncategorised climb to the finish was the main obstacle between the riders and stage glory, and looked to suit the likes of Ardennes Classic riders like Valverde or his compatriot Joaquim Rodriguez (Katusha).
As the gradient ramped up in the final three or so kilometres there was flurry of attacks off the front, while the group behind, which included the likes of Chris Froome (Team Sky) and race leader Esteban Chaves (Orica-GreenEdge), held back until the final ramp up to the finish.
2008 Olympic champion Samuel Sanchez (BMC) attacked along with Nicolas Roche (Team Sky), but neither were able to hold out as a downhill section ramped up again within the final kilometre to the line, with the uphill sprint breaking out behind.
Stage three's winner Peter Sagan (Tinkoff-Saxo) held on to give himself a chance at making it two in a row, but found him in the familiar position of second at the end of the day after Valverde held out to cross the line first to take the stage victory.
Earlier in the day six men, Mickael Delage (FDJ), Bert Jan Lindeman (LottoNL-Jumbo), Nikolas Maes (Etixx-Quick Step), Jimmy Engoulvent (Europcar), Kristijan Durasek (Lampre-Merida), Markel Irizar (Trek Factory Racing), got away early into a breakaway and by 30km gone, had 13 minutes on the peloton behind.
That gap was gradually reduced over the course of the 209.6km day, before the final remnants were caught with around 11km remaining as the pace ramped up towards the base of the final climb.
The GC remains relatively unchanged after the stage, with the top-10, including Britain's Froome, finishing within touching distance of the stage winner.
Colombian Chaves holds on to the leader's red jersey for a third day as the peloton head to a probable sprint stage on the Vuelta's fifth day, with a 167.3km route from Rota Alcala de Guardaira.
Vuelta a España stage four: Estepona - Vejer de la Frontera (209.6km)
1. Alejandro Valverde (Esp) Movistar, in 5-07-30
2. Peter Sagan (Slo) Tinkoff-Saxo
3. Daniel Moreno (Esp) Katusha
4. Nicolas Roche (Ire) Team Sky
5. Jose Goncalves (Por) Caja Rural
6. Joaquim Rodriguez (Esp) Katusha, all same time
7. Julien Simon (Fra) Cofidis, at 3 secs
8. Rafal Majka (Pol) Tinkoff-Saxo
9. Nairo Quintana (Col) Movistar
10. Esteban Chaves (Col) Orica-GreenEdge, all same time
Overall classification after stage four
1. Esteban Chaves (Col) Orica-Green-Edge, in 13-11-34
2. Tom Dumoulin (Ned) Giant-Alpecin at 5s
3. Nicolas Roche (Irl) Team Sky at 12s
4. Daniel Martin (Irl) Cannondale-Garmin at 24s
5. Alejandro Valverde (Esp) Movistar at 25s
6. Joaquim Rodriguez (Esp) Katusha at 32s
9. Daniel Moreno (Esp) Katusha at 33 secs
8. Nairo Quintana (Col) Movistar 36s
9. Chris Froome (GBr) Team Sky at 40s
10. Fabio Aru (Ita) Astana 47s
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