Sonji is a rare variant of Sonja that was most common in the 1960s and has all but disappeared.
Sonji is a girl name. It last appears in U.S. records in 1991. Sonji first appears in 1951 and peaked in 1966 (225 births).
| Year | U.S. births | U.S. + territories | Rank |
|---|---|---|---|
| 1991 | 6 | — | #12,928 |
| 1988 | 5 | — | #13,603 |
| 1986 | 5 | — | #12,567 |
| 1983 | 6 | — | #10,099 |
| 1981 | 5 | — | #11,938 |
| 1980 | 8 | — | #8,063 |
| 1979 | 7 | — | #8,882 |
| 1978 | 8 | — | #7,552 |
| 1977 | 13 | — | #5,168 |
| 1976 | 12 | — | #5,154 |
| 1975 | 6 | — | #8,893 |
| 1974 | 9 | — | #6,179 |
| 1973 | 26 | — | #2,738 |
| 1972 | 41 | — | #1,987 |
| 1971 | 50 | — | #1,794 |
| 1970 | 39 | — | #2,113 |
| 1969 | 75 | — | #1,314 |
| 1968 | 69 | — | #1,343 |
| 1967 | 98 | — | #1,044 |
| 1966 | 225 | — | #639 |
| 1965 | 96 | — | #1,074 |
| 1964 | 35 | — | #2,036 |
| 1963 | 8 | — | #5,232 |
| 1962 | 8 | — | #5,238 |
| 1961 | 7 | — | #5,764 |
| 1960 | 8 | — | #5,120 |
| 1958 | 5 | — | #6,903 |
| 1955 | 5 | — | #6,603 |
| 1954 | 5 | — | #6,515 |
| 1953 | 8 | — | #4,551 |
| 1951 | 6 | — | #5,341 |