The West Indies won the toss and chose to bat on the final match at Kensington Oval but made only 43 runs. Freya Davies ended with figures of 3-2 and Alice Davidson-Richards 3-5.
It was a score swiftly defeated by England, who achieved 44 runs for just two wickets.
England claimed the series victory to go with their ODI sweep after defeating the West Indies by 17 runs in the third game a week ago.
The team now moves on to the T20 World Cup in South Africa in February.
“On the pitch it’s been brilliant but we haven’t massively been challenged which is a shame,” said Heather Knight.
“It’s felt weirdly like a very low key tour, no media here and not a huge amount of coverage. And not having third umpires and DRS feels really strange, almost like going back in time a little bit.
“With those things, you just become accustomed to it, you have those things in domestic competitions back home. But ultimately it’s all about money being available to put into those resources.
“With the T20 World Cup coming it’s going to be very different and very much in the spotlight.”
Additional reporting by PA.