readxlsb

Import ‘Excel’ binary (.xlsb) workbooks into R

Not on CRAN… yet… but give it a go

library(devtools)
install_github("velofrog/readxlsb")

library(readxlsb)
read_xlsb(path = system.file("extdata", "TestBook.xlsb", package="readxlsb"), range="PORTFOLIO")