That's even lower than the previous record low of 4.5 percent that was set in December.
However, it's a fraction higher than the national unemployment rate for January, which was 4.1 percent.
Figures released Wednesday by the state Employment Development Department show that California employers added 35,500 non-farm payroll jobs in January. About 17 million Californians held such jobs.
The largest increase was in the construction sector, followed by trade, transportation and utilities.
California has gained nearly 3 million jobs in an economic expansion that began in 2010.