Codex Boernerianus, designated by G^p, G₃ or 012 (in the Gregory-Aland numbering of New Testament manuscripts), α 1028 (in the von Soden numbering of New Testament manuscripts), is a small New Testament manuscript made of parchment which contains the majority of the Pauline epistles. Using the study of comparative writing styles (paleography), the manuscript has been dated to the 9th century CE. The name of the codex derives from the theology professor Christian Frederick Boerner, to whom it once belonged. The manuscript has several gaps.

The manuscript is a codex (precursor to the modern book), containing the text of the Pauline epistles (excluding Hebrews). The text is written in one column per page, 20 lines per page (sized 25 x 18 cm) on 99 vellum leaves. The main text is in Greek with an interlinear Latin translation inserted above the Greek text, in the same manner as Codex Sangallensis 48 (Δ).

The text of the codex contains six gaps (Romans 1:1-4, 2:17-24, 1 Cor. 3:8-16, 6:7-14, Col. 2:1-8, Philem. 21-25). Quotations from the Old Testament are marked in the left-hand margin by inverted commas (>; also known as a diplai), and Latin notation identifies a quotation (f.e. Iesaia / Isaiah). Capital letters follow regular in stichometric frequency. This means the codex was copied from a manuscript arranged in lines (known as στίχοι / stichoi).

The codex sometimes uses minuscule letters: α, κ, ρ (of the same size as the uncials). It does not include rough breathing, smooth breathing or accent markers (usually used to mark stress or pitch). The Latin text is written in minuscule letters. The shape of some of the Latin letters - r, s, and t - is characteristic of the Anglo-Saxon alphabet.

The codex does not include the phrase ἐν Ῥώμῃ (in Rome), with Rom 1:7 employing ἐν ἀγαπῃ (in love) in its stead (Latin text – in caritate et dilectione / in charity and love), and in 1:15 the phrase is omitted entirely in both the Greek and Latin lines.

At the end of the codex, after the end of Philemon, stands the title Προς Λαουδακησας αρχεται επιστολη, with the interlinear Latin reading ad Laudicenses incipit epistola (both mean To the Laodiceans; the beginning of the letter). Below the title, the Latin text of the apocryphal Epistle to the Laodiceans is written - but there is no Greek interlinear text accompanying it.

The Greek text of this codex is considered a representative of the Western text-type. The text-types are groups of different New Testament manuscripts which share specific or generally related readings, which then differ from each other group, and thus the conflicting readings can separate out the groups. These are then used to determine the original text as published; there are three main groups with names: Alexandrian, Western, and Byzantine. Textual critic Kurt Aland placed it in Category III according to his New Testament manuscript text classification system. Category III manuscripts are described as having "a small but not a negligible proportion of early readings, with a considerable encroachment of [Byzantine] readings, and significant readings from other sources as yet unidentified".

The section 1 Corinthians 14:34–35 is placed after 1 Corinthians 14:40, as seen in other manuscripts considered to be of the Western text-type such as Claromontanus (D^p), Augiensis (F^p), Minuscule 88, it^{d, g}, and some manuscripts of the Latin Vulgate. It also does not contain the ending of Romans (Romans 16:25–27), but it has a blank space at Romans 14:23 for it which was never written.