| Election Name: | September 1870 Portuguese legislative election |
| Country: | Portugal |
| Flag Year: | 1830 |
| Type: | Parliamentary |
| Previous Election: | March 1870 Portuguese legislative election |
| Previous Year: | Mar 1870 |
| Next Election: | 1871 Portuguese legislative election |
| Next Year: | 1871 |
| Majority Seats: | 54 |
| Election Date: | 18 September 1870 |
| Colour5: | 0070C0 |
| Leader Since5: | 1856 |
| Last Election5: | 14 seats |
| Seats5: | 12 |
| Seats After5: | 2 |
| Colour2: | 800000 |
| Leader Since2: | 1852 |
| Last Election2: | 75 seats |
| Seats2: | 20 |
| Seats After2: | 55 |
| Colour1: | 953735 |
| Leader Since1: | 1869 |
| Last Election1: | 15 seats |
| Seats1: | 59 |
| Seats After1: | 44 |
| Colour4: | D46A4C |
| Party4: | Avilists |
| Leader Since4: | 1870 |
| Last Election4: | New |
| Seats4: | 16 |
| Seats After4: | New |
| Posttitle: | Prime Minister after election |
| After Party: | Reformist |
Parliamentary elections were held in Portugal on 18 September 1870.
| Party | Votes | % | Seats |
|---|---|---|---|
| Reformist Party | 59 | ||
| Historic Party | 20 | ||
| Avilistas | 16 | ||
| Regenerator Party | 12 | ||
| Total | 230,789 | 107 | |
| Registered voters/turnout | 422,642 | 54.6 | – |
| align=left colspan=4 | Source: ISCSP, Nohlen & Stöver[1] | ||