The 1909 Rangitikei by-election was a by-election held during the 17th New Zealand Parliament in the Rangitikei electorate of the North Island. This was the sixth by-election since the Rangitikei electorate was established for the 1861 election. The previous by-election took place in 1892 and the following one took place in 1978. The Second Ballot Act 1908 was in force and in the first ballot, and Frank Hockly of the opposition Reform Party won the first ballot, but Robert William Smith of the governing Liberal Party was ultimately chosen in the second ballot.

The 17th New Zealand Parliament was a term of the New Zealand Parliament. It was elected at the 1908 general election in November and December of that year.