diff --git a/docs/configuration/storage.md b/docs/configuration/storage.md
index 04873ee36..0c5b1e9ba 100644
--- a/docs/configuration/storage.md
+++ b/docs/configuration/storage.md
@@ -101,6 +101,20 @@ storage-s3-secret-key: ""
 # Default: ""
 storage-s3-bucket: ""
 
+
+# String. Key prefix to use for the S3 storage.
+# This is optional.
+#
+# Prefix must end with a trailing slash.
+#
+# This is useful if you want to store multiple instances in the same bucket,
+# or if you want to store your data in a subdirectory of the bucket.
+# This has no effect if the storage backend isn't "s3".
+#
+# Examples: ["gts-instance1/", "gts-instance2/"]
+# Default: ""
+storage-s3-key-prefix: ""
+
 # String. Bucket lookup type.
 #
 # If you know what kind of bucket lookup type you need you can specify it here.
diff --git a/internal/cleaner/media.go b/internal/cleaner/media.go
index 6384ba368..043d7cf5f 100644
--- a/internal/cleaner/media.go
+++ b/internal/cleaner/media.go
@@ -20,6 +20,7 @@ package cleaner
 import (
 	"context"
 	"errors"
+	"strings"
 	"time"
 
 	"code.superseriousbusiness.org/gotosocial/internal/db"
@@ -96,6 +97,7 @@ func (m *Media) PruneOrphaned(ctx context.Context) (int, error) {
 	// All media files in storage will have path fitting: {$account}/{$type}/{$size}/{$id}.{$ext}
 	if err := m.state.Storage.WalkKeys(ctx, func(path string) error {
 		// Check for our expected fileserver path format.
+		path = strings.TrimPrefix(path, m.state.Storage.KeyPrefix)
 		if !regexes.FilePath.MatchString(path) {
 			log.Warnf(ctx, "unexpected storage item: %s", path)
 			return nil
diff --git a/internal/config/config.go b/internal/config/config.go
index f051ab005..d9293e062 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -135,6 +135,7 @@ type Configuration struct {
 	StorageS3Proxy        bool   `name:"storage-s3-proxy" usage:"Proxy S3 contents through GoToSocial instead of redirecting to a presigned URL"`
 	StorageS3RedirectURL  string `name:"storage-s3-redirect-url" usage:"Custom URL to use for redirecting S3 media links. If set, this will be used instead of the S3 bucket URL."`
 	StorageS3BucketLookup string `name:"storage-s3-bucket-lookup" usage:"S3 bucket lookup type to use. Can be 'auto', 'dns' or 'path'. Defaults to 'auto'."`
+	StorageS3KeyPrefix    string `name:"storage-s3-key-prefix" usage:"Prefix to use for S3 keys. This is useful for separating multiple instances sharing the same S3 bucket."`
 
 	StatusesMaxChars           int `name:"statuses-max-chars" usage:"Max permitted characters for posted statuses, including content warning"`
 	StatusesPollMaxOptions     int `name:"statuses-poll-max-options" usage:"Max amount of options permitted on a poll"`
diff --git a/internal/config/helpers.gen.go b/internal/config/helpers.gen.go
index 38f33c67e..0803bab08 100644
--- a/internal/config/helpers.gen.go
+++ b/internal/config/helpers.gen.go
@@ -104,6 +104,7 @@ func (cfg *Configuration) RegisterFlags(flags *pflag.FlagSet) {
 	flags.Bool("storage-s3-proxy", cfg.StorageS3Proxy, "Proxy S3 contents through GoToSocial instead of redirecting to a presigned URL")
 	flags.String("storage-s3-redirect-url", cfg.StorageS3RedirectURL, "Custom URL to use for redirecting S3 media links. If set, this will be used instead of the S3 bucket URL.")
 	flags.String("storage-s3-bucket-lookup", cfg.StorageS3BucketLookup, "S3 bucket lookup type to use. Can be 'auto', 'dns' or 'path'. Defaults to 'auto'.")
+	flags.String("storage-s3-key-prefix", cfg.StorageS3KeyPrefix, "Prefix to use for S3 keys. This is useful for separating multiple instances sharing the same S3 bucket.")
 	flags.Int("statuses-max-chars", cfg.StatusesMaxChars, "Max permitted characters for posted statuses, including content warning")
 	flags.Int("statuses-poll-max-options", cfg.StatusesPollMaxOptions, "Max amount of options permitted on a poll")
 	flags.Int("statuses-poll-option-max-chars", cfg.StatusesPollOptionMaxChars, "Max amount of characters for a poll option")
@@ -285,6 +286,7 @@ func (cfg *Configuration) MarshalMap() map[string]any {
 	cfgmap["storage-s3-proxy"] = cfg.StorageS3Proxy
 	cfgmap["storage-s3-redirect-url"] = cfg.StorageS3RedirectURL
 	cfgmap["storage-s3-bucket-lookup"] = cfg.StorageS3BucketLookup
+	cfgmap["storage-s3-key-prefix"] = cfg.StorageS3KeyPrefix
 	cfgmap["statuses-max-chars"] = cfg.StatusesMaxChars
 	cfgmap["statuses-poll-max-options"] = cfg.StatusesPollMaxOptions
 	cfgmap["statuses-poll-option-max-chars"] = cfg.StatusesPollOptionMaxChars
@@ -1029,6 +1031,14 @@ func (cfg *Configuration) UnmarshalMap(cfgmap map[string]any) error {
 		}
 	}
 
+	if ival, ok := cfgmap["storage-s3-key-prefix"]; ok {
+		var err error
+		cfg.StorageS3KeyPrefix, err = cast.ToStringE(ival)
+		if err != nil {
+			return fmt.Errorf("error casting %#v -> string for 'storage-s3-key-prefix': %w", ival, err)
+		}
+	}
+
 	if ival, ok := cfgmap["statuses-max-chars"]; ok {
 		var err error
 		cfg.StatusesMaxChars, err = cast.ToIntE(ival)
@@ -3793,6 +3803,31 @@ func GetStorageS3BucketLookup() string { return global.GetStorageS3BucketLookup(
 // SetStorageS3BucketLookup safely sets the value for global configuration 'StorageS3BucketLookup' field
 func SetStorageS3BucketLookup(v string) { global.SetStorageS3BucketLookup(v) }
 
+// StorageS3KeyPrefixFlag returns the flag name for the 'StorageS3KeyPrefix' field
+func StorageS3KeyPrefixFlag() string { return "storage-s3-key-prefix" }
+
+// GetStorageS3KeyPrefix safely fetches the Configuration value for state's 'StorageS3KeyPrefix' field
+func (st *ConfigState) GetStorageS3KeyPrefix() (v string) {
+	st.mutex.RLock()
+	v = st.config.StorageS3KeyPrefix
+	st.mutex.RUnlock()
+	return
+}
+
+// SetStorageS3KeyPrefix safely sets the Configuration value for state's 'StorageS3KeyPrefix' field
+func (st *ConfigState) SetStorageS3KeyPrefix(v string) {
+	st.mutex.Lock()
+	defer st.mutex.Unlock()
+	st.config.StorageS3KeyPrefix = v
+	st.reloadToViper()
+}
+
+// GetStorageS3KeyPrefix safely fetches the value for global configuration 'StorageS3KeyPrefix' field
+func GetStorageS3KeyPrefix() string { return global.GetStorageS3KeyPrefix() }
+
+// SetStorageS3KeyPrefix safely sets the value for global configuration 'StorageS3KeyPrefix' field
+func SetStorageS3KeyPrefix(v string) { global.SetStorageS3KeyPrefix(v) }
+
 // StatusesMaxCharsFlag returns the flag name for the 'StatusesMaxChars' field
 func StatusesMaxCharsFlag() string { return "statuses-max-chars" }
 
diff --git a/internal/storage/storage.go b/internal/storage/storage.go
index 780d2ca5d..32e9ccd27 100644
--- a/internal/storage/storage.go
+++ b/internal/storage/storage.go
@@ -78,27 +78,32 @@ type Driver struct {
 	// S3-only parameters
 	Proxy          bool
 	Bucket         string
+	KeyPrefix      string
 	PresignedCache *ttl.Cache[string, PresignedURL]
 	RedirectURL    string
 }
 
 // Get returns the byte value for key in storage.
 func (d *Driver) Get(ctx context.Context, key string) ([]byte, error) {
+	key = d.KeyPrefix + key
 	return d.Storage.ReadBytes(ctx, key)
 }
 
 // GetStream returns an io.ReadCloser for the value bytes at key in the storage.
 func (d *Driver) GetStream(ctx context.Context, key string) (io.ReadCloser, error) {
+	key = d.KeyPrefix + key
 	return d.Storage.ReadStream(ctx, key)
 }
 
 // Put writes the supplied value bytes at key in the storage
 func (d *Driver) Put(ctx context.Context, key string, value []byte) (int, error) {
+	key = d.KeyPrefix + key
 	return d.Storage.WriteBytes(ctx, key, value)
 }
 
 // PutFile moves the contents of file at path, to storage.Driver{} under given key (with content-type if supported).
 func (d *Driver) PutFile(ctx context.Context, key, filepath, contentType string) (int64, error) {
+	key = d.KeyPrefix + key
 	// Open file at path for reading.
 	file, err := os.Open(filepath)
 	if err != nil {
@@ -144,11 +149,13 @@ func (d *Driver) PutFile(ctx context.Context, key, filepath, contentType string)
 
 // Delete attempts to remove the supplied key (and corresponding value) from storage.
 func (d *Driver) Delete(ctx context.Context, key string) error {
+	key = d.KeyPrefix + key
 	return d.Storage.Remove(ctx, key)
 }
 
 // Has checks if the supplied key is in the storage.
 func (d *Driver) Has(ctx context.Context, key string) (bool, error) {
+	key = d.KeyPrefix + key
 	stat, err := d.Storage.Stat(ctx, key)
 	return (stat != nil), err
 }
@@ -156,6 +163,7 @@ func (d *Driver) Has(ctx context.Context, key string) (bool, error) {
 // WalkKeys walks the keys in the storage.
 func (d *Driver) WalkKeys(ctx context.Context, walk func(string) error) error {
 	return d.Storage.WalkKeys(ctx, storage.WalkKeysOpts{
+		Prefix: d.KeyPrefix,
 		Step: func(entry storage.Entry) error {
 			return walk(entry.Key)
 		},
@@ -164,6 +172,7 @@ func (d *Driver) WalkKeys(ctx context.Context, walk func(string) error) error {
 
 // URL will return a presigned GET object URL, but only if running on S3 storage with proxying disabled.
 func (d *Driver) URL(ctx context.Context, key string) *PresignedURL {
+	key = d.KeyPrefix + key
 	// Check whether S3 *without* proxying is enabled
 	s3, ok := d.Storage.(*s3.S3Storage)
 	if !ok || d.Proxy {
@@ -349,6 +358,7 @@ func NewS3Storage() (*Driver, error) {
 	return &Driver{
 		Proxy:          config.GetStorageS3Proxy(),
 		Bucket:         config.GetStorageS3BucketName(),
+		KeyPrefix:      config.GetStorageS3KeyPrefix(),
 		Storage:        s3,
 		PresignedCache: presignedCache,
 		RedirectURL:    redirectURL,
diff --git a/test/envparsing.sh b/test/envparsing.sh
index 4fe13b6ac..3f8a55fda 100755
--- a/test/envparsing.sh
+++ b/test/envparsing.sh
@@ -187,6 +187,7 @@ EXPECT=$(cat << "EOF"
     "storage-s3-bucket": "gts",
     "storage-s3-bucket-lookup": "auto",
     "storage-s3-endpoint": "localhost:9000",
+    "storage-s3-key-prefix": "",
     "storage-s3-proxy": true,
     "storage-s3-redirect-url": "",
     "storage-s3-secret-key": "miniostorage",
@@ -208,7 +209,7 @@ EXPECT=$(cat << "EOF"
 EOF
 )
 
-# Set all the environment variables to 
+# Set all the environment variables to
 # ensure that these are parsed without panic
 OUTPUT=$(GTS_LOG_LEVEL='info' \
 GTS_LOG_TIMESTAMP_FORMAT="banana" \